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Complete rewrite of the documentation.

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411
gitlab-pages/docs/advanced/entrypoints-contracts.md
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@ -1,173 +1,227 @@
---
id: entrypoints-contracts
title: Entrypoints, Contracts
title: Entrypoints to Contracts
---
## Entrypoints
Each LIGO smart contract is essentially a single main function, referring to the following types:
A LIGO contract is made of a series of constant and function
declarations. Only functions having a special type can be called when
the contract is activated: they are called *entrypoints*. An
entrypoint need to take two parameters, the *contract parameter* and
the *on-chain storage*, and return a pair made of a *list of
operations* and a (new) storage.
When the contract is originated, the initial value of the storage is
provided. When and entrypoint is later called, only the parameter is
provided, but the type of an entrypoint contains both.
The type of the contract parameter and the storage are up to the
contract designer, but the type for list operations is not. The return
type of an entrypoint is as follows, assuming that the type `storage`
has been defined elsewhere. (Note that you can use any type with any
name for the storage.)
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=a
type parameter_t is unit
type storage_t is unit
type return_t is (list(operation) * storage_t)
```pascaligo skip
type storage is ... // Any name, any type
type return is list (operation) * storage
```
<!--CameLIGO-->
```cameligo group=a
type parameter_t = unit
type storage_t = unit
type return_t = (operation list * storage_t)
```cameligo skip
type storage = ... // Any name, any type
type return = operation list * storage
```
<!--ReasonLIGO-->
```reasonligo group=a
type parameter_t = unit;
type storage_t = unit;
type return_t = (list(operation) , storage_t);
```reasonligo skip
type storage = ...; // Any name, any type
type return = (list (operation), storage);
```
<!--END_DOCUSAURUS_CODE_TABS-->
Each main function receives two arguments:
- `parameter` - this is the parameter received in the invocation operation
- `storage` - this is the current (real) on-chain storage value
The contract storage can only be modified by activating an
entrypoint. It is important to understand what that means. What it
does *not* mean is that some global variable holding the storage is
modified by the entrypoint. Instead, what it *does* mean is that,
given the state of the storage *on-chain*, an entrypoint specifies how
to create another state for it, depending on a parameter.
Storage can only be modified by running the smart contract entrypoint, which is responsible for returning a pair holding a list of operations, and a new storage.
Here is an example of a smart contract main function:
> 💡 The contract below literally does *nothing*
Here is an example where the storage is a single natural number that
is updated by the parameter.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=a
function main(const parameter: parameter_t; const store: storage_t): return_t is
((nil : list(operation)), store)
type storage is nat
type return is list (operation) * storage
function save (const parameter : nat; const store : storage) : return is
((nil : list (operation)), parameter)
```
<!--CameLIGO-->
```cameligo group=a
let main (parameter, store: parameter_t * storage_t) : return_t =
(([]: operation list), store)
type storage = nat
let save (parameter, store: nat * storage) : return =
(([] : operation list), parameter)
```
<!--ReasonLIGO-->
```reasonligo group=a
let main = ((parameter, store): (parameter_t, storage_t)) : return_t => {
(([]: list(operation)), store);
type storage = nat;
let main = ((parameter, store): (nat, storage)) : return => {
(([] : list (operation)), parameter);
};
```
<!--END_DOCUSAURUS_CODE_TABS-->
A contract entrypoints are the constructors of the parameter type (variant) and you must use pattern matching (`case`, `match`, `switch`) on the parameter in order to associate each entrypoint to its corresponding handler.
In LIGO, the design pattern for entrypoints consists in actually
having exactly *one entrypoint*, like the `main` function in C. The
parameter of the contract is then a variant type, and, depending on
the constructors of that type, different functions in the contract are
called. In other terms, the unique entrypoint dispatches the control
flow depending on a *pattern matching* on the contract parameter.
To access the 'entrypoints' of a contract, we define a main function whose parameter is a variant type with constructors for each entrypoint. This allows us to satisfy the requirement that LIGO contracts always begin execution from the same function. The main function simply takes this variant, pattern matches it to determine which entrypoint to dispatch the call to, then returns the result of executing that entrypoint with the projected arguments.
> The LIGO variant's are compiled to a Michelson annotated tree of union type.
In the following example, the storage contains a counter (of type
`nat`) and a name (of type `string`). Depending on the parameter of
the contract, either the counter or the name is updated.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=recordentry
type parameter_t is
| Entrypoint_a of int
| Entrypoint_b of string
type storage_t is unit
type return_t is (list(operation) * storage_t)
```pascaligo group=b
type parameter is
Entrypoint_A of nat
| Entrypoint_B of string
function handle_a (const p : int; const store : storage_t) : return_t is
((nil : list(operation)), store)
type storage is record [
counter : nat;
name : string
]
function handle_b (const p : string; const store : storage_t) : return_t is
((nil : list(operation)), store)
type return is list (operation) * storage
function main(const parameter: parameter_t; const store: storage_t): return_t is
case parameter of
| Entrypoint_a (p) -> handle_a(p,store)
| Entrypoint_b (p) -> handle_b(p,store)
function handle_A (const n : nat; const store : storage) : return is
((nil : list (operation)), store with record [counter = n])
function handle_B (const s : string; const store : storage) : return is
((nil : list (operation)), store with record [name = s])
function main (const param : parameter; const store : storage): return is
case param of
Entrypoint_A (n) -> handle_A (n, store)
| Entrypoint_B (s) -> handle_B (s, store)
end
```
<!--CameLIGO-->
```cameligo group=recordentry
type parameter_t =
| Entrypoint_a of int
| Entrypoint_b of string
type storage_t = unit
type return_t = (operation list * storage_t)
```cameligo group=b
type parameter =
Entrypoint_A of nat
| Entrypoint_B of string
let handle_a (parameter, store: int * storage_t) : return_t =
(([]: operation list), store)
type storage = {
counter : nat;
name : string
}
let handle_b (parameter, store: string * storage_t) : return_t =
(([]: operation list), store)
type return = operation list * storage
let main (parameter, store: parameter_t * storage_t) : return_t =
match parameter with
| Entrypoint_a p -> handle_a (p,store)
| Entrypoint_b p -> handle_b (p,store)
let handle_A (n, store : nat * storage) : return =
([] : operation list), {store with counter = n}
let handle_B (s, store : string * storage) : return =
([] : operation list), {store with name = s}
let main (param, store: parameter * storage) : return =
match param with
Entrypoint_A n -> handle_A (n, store)
| Entrypoint_B s -> handle_B (s, store)
```
<!--ReasonLIGO-->
```reasonligo group=recordentry
type parameter_t =
| Entrypoint_a(int)
| Entrypoint_b(string);
type storage_t = unit;
type return_t = (list(operation) , storage_t);
```reasonligo group=b
type parameter =
| Entrypoint_A (nat)
| Entrypoint_B (string);
let handle_a = ((parameter, store): (int, storage_t)) : return_t => {
(([]: list(operation)), store); };
type storage = {
counter : nat,
name : string
};
let handle_b = ((parameter, store): (string, storage_t)) : return_t => {
(([]: list(operation)), store); };
type return = (list (operation), storage);
let main = ((parameter, store): (parameter_t, storage_t)) : return_t => {
switch (parameter) {
| Entrypoint_a(p) => handle_a((p,store))
| Entrypoint_b(p) => handle_b((p,store))
let handle_A = ((n, store): (nat, storage)) : return => {
(([] : list (operation)), {...store, counter : n}); };
let handle_B = ((s, store): (string, storage)) : return => {
(([] : list (operation)), {...store, name : s}); };
let main = ((param, store): (parameter, storage)) : return => {
switch (param) {
| Entrypoint_A (n) => handle_A ((n, store))
| Entrypoint_B (s) => handle_B ((s, store))
}
};
```
<!--END_DOCUSAURUS_CODE_TABS-->
## Built-in contract variables
## Tezos-specific Built-ins
Each LIGO smart contract deployed on the Tezos blockchain, has access to certain built-in variables/constants that can be used to determine a range
of useful things. In this section you'll find how those built-ins can be utilized.
A LIGO smart contract can query part of the state of the Tezos
blockchain by means of built-in values. In this section you will find
how those built-ins can be utilized.
### Accepting/declining money in a smart contract
### Accepting or Declining Tokens in a Smart Contract
This example shows how `amount` and `failwith` can be used to decline a transaction that sends more tez than `0mutez`.
This example shows how `amount` and `failwith` can be used to decline
any transaction that sends more tez than `0mutez`, that is, no
incoming tokens are accepted.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=b
function main (const p : unit ; const s : unit) : (list(operation) * unit) is
block {
if amount > 0mutez then failwith("This contract does not accept tez") else skip
} with ((nil : list(operation)), unit);
```pascaligo group=c
type parameter is unit
type storage is unit
type return is list (operation) * storage
function deny (const param : parameter; const store : storage) : return is
if amount > 0mutez then
(failwith ("This contract does not accept tokens.") : return)
else ((nil : list (operation)), store)
```
<!--CameLIGO-->
```cameligo group=b
let main (p, s: unit * unit) : operation list * unit =
if amount > 0mutez
then (failwith "This contract does not accept tez": operation list * unit)
else (([]: operation list), unit)
```cameligo group=c
type parameter = unit
type storage = unit
type return = operation list * storage
let deny (param, store : parameter * storage) : return =
if amount > 0mutez then
(failwith "This contract does not accept tokens.": return)
else (([] : operation list), store)
```
<!--ReasonLIGO-->
```reasonligo group=b
let main = ((p,s): (unit, unit)) : (list(operation), unit) => {
```reasonligo group=c
type parameter = unit;
type storage = unit;
type return = (list (operation), storage);
let deny = ((param, store): (parameter, storage)) : return => {
if (amount > 0mutez) {
(failwith("This contract does not accept tez"): (list(operation), unit));
}
else {
(([]: list(operation)), ());
};
(failwith("This contract does not accept tokens."): return); }
else { (([] : list (operation)), store); };
};
```
@ -181,127 +235,164 @@ This example shows how `sender` or `source` can be used to deny access to an ent
<!--Pascaligo-->
```pascaligo group=c
const owner : address = ("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address);
function main (const p : unit ; const s : unit) : (list(operation) * unit) is
block {
if source =/= owner then failwith("This address can't call the contract") else skip
} with ((nil : list(operation)), unit);
function filter (const param : parameter; const store : storage) : return is
if source =/= owner then (failwith ("Access denied.") : return)
else ((nil : list(operation)), store)
```
<!--CameLIGO-->
```cameligo group=c
let owner : address = ("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address)
let main (p,s: unit * unit) : operation list * unit =
if source <> owner
then (failwith "This address can't call the contract": operation list * unit)
else (([]: operation list), ())
let filter (param, store: parameter * storage) : return =
if source <> owner then (failwith "Access denied." : return)
else (([] : operation list), store)
```
<!--ReasonLIGO-->
```reasonligo group=c
let owner : address = ("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address);
let main = ((p,s): (unit, unit)) : (list(operation), unit) => {
if (source != owner) {
(failwith("This address can't call the contract"): (list(operation), unit));
}
else {
(([]: list(operation)), ());
};
let main = ((param, store): (parameter, storage)) : storage => {
if (source != owner) { (failwith ("Access denied.") : return); }
else { (([] : list (operation)), store); };
};
```
<!--END_DOCUSAURUS_CODE_TABS-->
### Cross contract calls
### Inter-Contract Invocations
This example shows how a contract can invoke another contract by emiting a transaction operation at the end of an entrypoint.
It would be somewhat misleading to speak of "contract calls", as this
wording may wrongly suggest an analogy between contract "calls" and
function "calls". Indeed, the control flow returns to the site of a
function call, and composed function calls therefore are *stacked*,
that is, they follow a last in, first out ordering. This is not what
happens when a contract invokes another: the invocation is *queued*,
that is, follows a first in, first our ordering, and the dequeuing
only starts at the normal end of a contract (no failure). That is why
we speak of "contract invocations" instead of "calls".
> The same technique can be used to transfer tez to an implicit account (tz1, ...), all you have to do is use `unit` instead of a parameter for a smart contract.
The following example shows how a contract can invoke another by
emiting a transaction operation at the end of an entrypoint.
In our case, we have a `counter.ligo` contract that accepts a parameter of type `action`, and we have a `proxy.ligo` contract that accepts the same parameter type, and forwards the call to the deployed counter contract.
> The same technique can be used to transfer tokens to an implicit
> account (tz1, ...): all you have to do is use a unit value as the
> parameter of the smart contract.
In our case, we have a `counter.ligo` contract that accepts a
parameter of type `action`, and we have a `proxy.ligo` contract that
accepts the same parameter type, and forwards the call to the deployed
counter contract.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo skip
// counter.ligo
type action is
| Increment of int
| Decrement of int
| Reset of unit
type parameter is
Increment of nat
| Decrement of nat
| Reset
type storage is unit
type return is list (operation) * storage
```
```pascaligo skip
```pascaligo group=d
// proxy.ligo
type action is
| Increment of int
| Decrement of int
| Reset of unit
type parameter is
Increment of nat
| Decrement of nat
| Reset
const dest: address = ("KT19wgxcuXG9VH4Af5Tpm1vqEKdaMFpznXT3": address);
type storage is unit
function proxy(const param: action; const store: unit): (list(operation) * unit)
is block {
const counter: contract(action) = get_contract(dest);
// re-use the param passed to the proxy in the subsequent transaction
// e.g.:
// const mockParam: action = Increment(5);
type return is list (operation) * storage
const dest : address = ("KT19wgxcuXG9VH4Af5Tpm1vqEKdaMFpznXT3" : address)
function proxy (const param : parameter; const store : storage): return is
block {
const counter : contract (parameter) = get_contract (dest);
(* Reuse the parameter in the subsequent
transaction or use another one, `mock_param`. *)
const mock_param : parameter = Increment (5n);
const op : operation = transaction (param, 0mutez, counter);
const opList: list(operation) = list op; end;
} with (opList, store)
const ops : list (operation) = list [op]
} with (ops, store)
```
<!--CameLIGO-->
```cameligo
```cameligo skip
// counter.mligo
type action =
| Increment of int
| Decrement of int
| Reset of unit
type paramater =
Increment of nat
| Decrement of nat
| Reset
// ...
```
```cameligo
```cameligo group=d
// proxy.mligo
type action =
| Increment of int
| Decrement of int
| Reset of unit
type parameter =
Increment of nat
| Decrement of nat
| Reset
type storage = unit
type return = operation list * storage
let dest : address = ("KT19wgxcuXG9VH4Af5Tpm1vqEKdaMFpznXT3" : address)
let proxy (param, storage: action * unit): operation list * unit =
let counter: action contract = Operation.get_contract dest in
let op: operation = Operation.transaction param 0mutez counter in
[op], storage
let proxy (param, store : parameter * storage) : return =
let counter : parameter contract = Operation.get_contract dest in
(* Reuse the parameter in the subsequent
transaction or use another one, `mock_param`. *)
let mock_param : parameter = Increment (5n) in
let op : operation = Operation.transaction param 0mutez counter
in [op], store
```
<!--ReasonLIGO-->
```reasonligo
```reasonligo skip
// counter.religo
type action =
| Increment(int)
| Decrement(int)
| Reset(unit);
type parameter =
| Increment (nat)
| Decrement (nat)
| Reset
// ...
```
```reasonligo
```reasonligo group=d
// proxy.religo
type action =
| Increment(int)
| Decrement(int)
| Reset(unit);
type parameter =
| Increment (nat)
| Decrement (nat)
| Reset;
type storage = unit;
type return = (list (operation), storage);
let dest : address = ("KT19wgxcuXG9VH4Af5Tpm1vqEKdaMFpznXT3" : address);
let proxy = ((param, s): (action, unit)): (list(operation), unit) =>
let counter: contract(action) = Operation.get_contract(dest);
let proxy = ((param, store): (parameter, storage)) : return =>
let counter : contract (parameter) = Operation.get_contract (dest);
(* Reuse the parameter in the subsequent
transaction or use another one, `mock_param`. *)
let mock_param : parameter = Increment (5n);
let op : operation = Operation.transaction (param, 0mutez, counter);
([op], s);
([op], store);
```
<!--END_DOCUSAURUS_CODE_TABS-->

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gitlab-pages/docs/advanced/src/entrypoints-contracts/amount.ligo
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@ -1,4 +0,0 @@
function main (const p : unit ; const s : unit) : (list(operation) * unit) is
block {
if amount > 0mutez then failwith("This contract does not accept tez") else skip
} with ((nil : list(operation)), unit);

5
gitlab-pages/docs/advanced/src/entrypoints-contracts/owner.ligo
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@ -1,5 +0,0 @@
const owner: address = ("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address);
function main (const p : unit ; const s : unit) : (list(operation) * unit) is
block {
if source =/= owner then failwith("This address can't call the contract") else skip
} with ((nil : list(operation)), unit);

9
gitlab-pages/docs/advanced/src/entrypoints-contracts/transaction/counter.ligo
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@ -1,9 +0,0 @@
#include "counter.types.ligo"
function counter (const p : action ; const s : int): (list(operation) * int) is
block { skip } with ((nil : list(operation)),
case p of
| Increment(n) -> s + n
| Decrement(n) -> s - n
| Reset(n) -> 0
end)

4
gitlab-pages/docs/advanced/src/entrypoints-contracts/transaction/counter.types.ligo
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@ -1,4 +0,0 @@
type action is
| Increment of int
| Decrement of int
| Reset of unit

14
gitlab-pages/docs/advanced/src/entrypoints-contracts/transaction/proxy.ligo
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@ -1,14 +0,0 @@
#include "counter.types.ligo"
// Replace the following address with your deployed counter contract address
const address: address = ("KT19wgxcuXG9VH4Af5Tpm1vqEKdaMFpznXT3": address);
function proxy(const param: action; const store: unit): (list(operation) * unit)
is block {
const counter: contract(action) = get_contract(address);
// re-use the param passed to the proxy in the subsequent transaction
// e.g.:
// const mockParam: action = Increment(5);
const op: operation = transaction(param, 0mutez, counter);
const opList: list(operation) = list op; end;
} with (opList, store)

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gitlab-pages/docs/advanced/src/timestamps/timestamp.ligo
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@ -1,9 +0,0 @@
const today: timestamp = now;
const one_day: int = 86400;
const in_24_hrs: timestamp = today + one_day;
const today: timestamp = now;
const one_day: int = 86400;
const a_24_hrs_ago: timestamp = today - one_day;
const not_tommorow: bool = (now = in_24_hrs)

97
gitlab-pages/docs/advanced/timestamps-addresses.md
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@ -5,17 +5,20 @@ title: Timestamps, Addresses
## Timestamps
Timestamps in LIGO, or in Michelson in general are available in smart contracts, while bakers baking the block (including the transaction in a block) are responsible for providing the given current timestamp for the contract.
LIGO features timestamps, as Michelson does, while bakers baking the
block (including the transaction in a block) are responsible for
providing the given current timestamp for the contract.
### Current time
You can obtain the current time using the built-in syntax specific expression, please be aware that it's up to the baker to set the current timestamp value.
### Current Time
You can obtain the current time using the built-in syntax specific
expression, please be aware that it is up to the baker to set the
current timestamp value.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=a
const today: timestamp = now;
const today : timestamp = now
```
<!--CameLIGO-->
@ -30,21 +33,24 @@ let today: timestamp = Current.time;
<!--END_DOCUSAURUS_CODE_TABS-->
> When running code with ligo CLI, the option `--predecessor-timestamp` allows you to control what `now` returns.
> When running code with ligo CLI, the option
> `--predecessor-timestamp` allows you to control what `now` returns.
### Timestamp arithmetic
### Timestamp Arithmetic
In LIGO, timestamps can be added with `int`(s), this enables you to set e.g. time constraints for your smart contracts like this:
In LIGO, timestamps can be added to integers, allowing you to set time
constraints on your smart contracts. Consider the following scenarios.
#### In 24 hours
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=b
const today: timestamp = now;
const one_day: int = 86400;
const in_24_hrs: timestamp = today + one_day;
const some_date: timestamp = ("2000-01-01T10:10:10Z" : timestamp);
const one_day_later: timestamp = some_date + one_day;
const today : timestamp = now
const one_day : int = 86400
const in_24_hrs : timestamp = today + one_day
const some_date : timestamp = ("2000-01-01T10:10:10Z" : timestamp)
const one_day_later : timestamp = some_date + one_day
```
<!--CameLIGO-->
@ -67,13 +73,14 @@ let one_day_later: timestamp = some_date + one_day;
<!--END_DOCUSAURUS_CODE_TABS-->
#### 24 hours ago
#### 24 hours Ago
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=c
const today: timestamp = now;
const one_day: int = 86400;
const in_24_hrs: timestamp = today - one_day;
const today : timestamp = now
const one_day : int = 86400
const in_24_hrs : timestamp = today - one_day
```
<!--CameLIGO-->
@ -92,9 +99,10 @@ let in_24_hrs: timestamp = today - one_day;
<!--END_DOCUSAURUS_CODE_TABS-->
### Comparing timestamps
### Comparing Timestamps
You can also compare timestamps using the same comparison operators as for numbers:
You can also compare timestamps using the same comparison operators as
for numbers.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
@ -116,66 +124,83 @@ let not_tomorrow: bool = (Current.time == in_24_hrs);
## Addresses
`address` is a LIGO datatype used for Tezos addresses (tz1, tz2, tz3, KT1, ...).
Here's how you can define an address:
The type `address` in LIGO is used to denote Tezos addresses (tz1,
tz2, tz3, KT1, ...). Currently, addresses are created by casting a
string to the type `address`. Beware of failures if the address is
invalid. Consider the following examples.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=d
const my_account: address = ("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address);
const my_account : address =
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address)
```
<!--CameLIGO-->
```cameligo group=d
let my_account: address = ("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address)
let my_account : address =
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address)
```
<!--ReasonLIGO-->
```reasonligo group=d
let my_account: address = ("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address);
let my_account : address =
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address);
```
<!--END_DOCUSAURUS_CODE_TABS-->
## Signatures
`signature` is a LIGO datatype used for Tezos signature (edsig, spsig).
The type `signature` in LIGO datatype is used for Tezos signature
(edsig, spsig). Signatures are created by casting a string. Beware of
failure if the signature is invalid.
Here's how you can define a signature:
Here is how you can define a signature:
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=e
const my_signature: signature = ("edsigthTzJ8X7MPmNeEwybRAvdxS1pupqcM5Mk4uCuyZAe7uEk68YpuGDeViW8wSXMrCi5CwoNgqs8V2w8ayB5dMJzrYCHhD8C7": signature);
const my_sig : signature =
("edsigthTzJ8X7MPmNeEwybRAvdxS1pupqcM5Mk4uCuyZAe7uEk68YpuGDeViW8wSXMrCi5CwoNgqs8V2w8ayB5dMJzrYCHhD8C7" :
signature)
```
<!--CameLIGO-->
```cameligo group=e
let my_signature: signature = ("edsigthTzJ8X7MPmNeEwybRAvdxS1pupqcM5Mk4uCuyZAe7uEk68YpuGDeViW8wSXMrCi5CwoNgqs8V2w8ayB5dMJzrYCHhD8C7": signature)
let my_sig : signature =
("edsigthTzJ8X7MPmNeEwybRAvdxS1pupqcM5Mk4uCuyZAe7uEk68YpuGDeViW8wSXMrCi5CwoNgqs8V2w8ayB5dMJzrYCHhD8C7" :
signature)
```
<!--ReasonLIGO-->
```reasonligo group=e
let my_signature: signature = ("edsigthTzJ8X7MPmNeEwybRAvdxS1pupqcM5Mk4uCuyZAe7uEk68YpuGDeViW8wSXMrCi5CwoNgqs8V2w8ayB5dMJzrYCHhD8C7": signature);
let my_sig : signature =
("edsigthTzJ8X7MPmNeEwybRAvdxS1pupqcM5Mk4uCuyZAe7uEk68YpuGDeViW8wSXMrCi5CwoNgqs8V2w8ayB5dMJzrYCHhD8C7" :
signature);
```
<!--END_DOCUSAURUS_CODE_TABS-->
## keys
## Keys
`key` is a LIGO datatype used for Tezos public key.
The type `key` in LIGO is used for Tezos public keys. Do not confuse
them with map keys. Keys are made by casting strings. Beware of
failure if the key is invalid.
Here's how you can define a key:
Here is how you can define a key.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=f
const my_key: key = ("edpkuBknW28nW72KG6RoHtYW7p12T6GKc7nAbwYX5m8Wd9sDVC9yav": key);
const my_key : key =
("edpkuBknW28nW72KG6RoHtYW7p12T6GKc7nAbwYX5m8Wd9sDVC9yav" : key)
```
<!--CameLIGO-->
```cameligo group=f
let my_key: key = ("edpkuBknW28nW72KG6RoHtYW7p12T6GKc7nAbwYX5m8Wd9sDVC9yav": key)
let my_key : key =
("edpkuBknW28nW72KG6RoHtYW7p12T6GKc7nAbwYX5m8Wd9sDVC9yav" : key)
```
<!--ReasonLIGO-->
```reasonligo group=f
let my_key: key = ("edpkuBknW28nW72KG6RoHtYW7p12T6GKc7nAbwYX5m8Wd9sDVC9yav": key);
let my_key : key =
("edpkuBknW28nW72KG6RoHtYW7p12T6GKc7nAbwYX5m8Wd9sDVC9yav" : key);
```
<!--END_DOCUSAURUS_CODE_TABS-->

144
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@ -1,19 +1,18 @@
---
id: boolean-if-else
title: Boolean, If, Else
title: Booleans and Conditionals
---
## Boolean
## Booleans
The type of a Boolean is `bool` and the possible values are `True` and `False`.
Here's how to define a boolean:
The type of a boolean value is `bool`. Here is how to define a boolean
value:
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=a
const a: bool = True;
const b: bool = False;
const a : bool = True // Notice the capital letter
const b : bool = False // Same.
```
<!--CameLIGO-->
```cameligo group=a
@ -29,33 +28,34 @@ let b: bool = false;
<!--END_DOCUSAURUS_CODE_TABS-->
## Comparing two values
## Comparing two Values
In LIGO, only values of the same type can be compared. We call these "comparable types." Comparable types include e.g. `int`, `nat`, `string`, `tez`, `timestamp`, `address`, ...
In LIGO, only values of the same type can be compared. Moreover, not
all values of the same type can be compared, only those with
*comparable types*, which is a concept lifted from
Michelson. Comparable types include, for instance, `int`, `nat`,
`string`, `tez`, `timestamp`, `address`, etc.
### Comparing strings
### Comparing Strings
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=b
const a: string = "Alice";
const b: string = "Alice";
// True
const c: bool = (a = b);
const a : string = "Alice"
const b : string = "Alice"
const c : bool = (a = b) // True
```
<!--CameLIGO-->
```cameligo group=b
let a : string = "Alice"
let b : string = "Alice"
// true
let c: bool = (a = b)
let c : bool = (a = b) // true
```
<!--ReasonLIGO-->
```reasonligo group=b
let a : string = "Alice";
let b : string = "Alice";
(* true *)
let c: bool = (a == b);
let c : bool = (a == b); // true
```
<!--END_DOCUSAURUS_CODE_TABS-->
@ -65,14 +65,14 @@ let c: bool = (a == b);
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=c
const a: int = 5;
const b: int = 4;
const c: bool = (a = b);
const d: bool = (a > b);
const e: bool = (a < b);
const f: bool = (a <= b);
const g: bool = (a >= b);
const h: bool = (a =/= b);
const a : int = 5
const b : int = 4
const c : bool = (a = b)
const d : bool = (a > b)
const e : bool = (a < b)
const f : bool = (a <= b)
const g : bool = (a >= b)
const h : bool = (a =/= b)
```
<!--CameLIGO-->
```cameligo group=c
@ -102,91 +102,83 @@ let h: bool = (a != b);
### Comparing tez
> 💡 Comparing `tez` values is especially useful when dealing with an `amount` sent in a transaction.
> 💡 Comparing `tez` values is especially useful when dealing with an
> amount sent in a transaction.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=d
const a: tez = 5mutez;
const b: tez = 10mutez;
const c: bool = (a = b);
const a : tez = 5mutez
const b : tez = 10mutez
const c : bool = (a = b) // false
```
<!--CameLIGO-->
```cameligo group=d
let a : tez = 5mutez
let b : tez = 10mutez
// false
let c: bool = (a = b)
let c : bool = (a = b) // false
```
<!--ReasonLIGO-->
```reasonligo group=d
let a : tez = 5mutez;
let b : tez = 10mutez;
(* false *)
let c: bool = (a == b);
let c : bool = (a == b); // false
```
<!--END_DOCUSAURUS_CODE_TABS-->
## Conditionals, if staments, and more
## Conditionals
Conditional logic is an important part of every real world program.
### If/else statements
Conditional logic enables to fork the control flow depending on the
state.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=e
const min_age: nat = 16n;
type magnitude is Small | Large // See variant types.
function is_adult(const age: nat): bool is
if (age > min_age) then True else False
function compare (const n : nat) : magnitude is
if n < 10n then Small (Unit) else Large (Unit) // Unit is needed for now.
```
> You can run the function above with
> ```
> ligo run-function -s pascaligo src/if-else.ligo is_adult 21n
> ```
You can run the `compare` function defined above using the LIGO compiler
like this:
```shell
ligo run-function
gitlab-pages/docs/language-basics/boolean-if-else/cond.ligo compare 21n'
# Outputs: Large (Unit)
```
<!--CameLIGO-->
```cameligo group=e
let min_age: nat = 16n
type magnitude = Small | Large // See variant types.
(**
This function is really obnoxious, but it showcases
how the if statement and it's syntax can be used.
Normally, you'd use `with (age > min_age)` instead.
*)
let is_adult (age: nat) : bool =
if (age > min_age) then true else false
let compare (n : nat) : magnitude =
if n < 10n then Small else Large
```
You can run the `compare` function defined above using the LIGO compiler
like this:
```shell
ligo run-function
gitlab-pages/docs/language-basics/boolean-if-else/cond.mligo compare 21n'
# Outputs: Large
```
<!--ReasonLIGO-->
```reasonligo group=e
let min_age: nat = 16n;
type magnitude = | Small | Large; // See variant types.
(**
This function is really obnoxious, but it showcases
how the if statement and it's syntax can be used.
Normally, you'd use `with (age > min_age)` instead.
*)
let is_adult = (age: nat): bool =>
if (age > min_age) {
true;
} else {
false;
};
let compare = (n : nat) : magnitude =>
if (n < 10n) { Small; } else { Large; };
```
> You can run the function above with
> ```
> ligo run-function -s reasonligo src/if-else.religo is_adult 21n
> ```
You can run the `compare` function defined above using the LIGO compiler
like this:
```shell
ligo run-function
gitlab-pages/docs/language-basics/boolean-if-else/cond.religo compare 21n'
# Outputs: Large
```
<!--END_DOCUSAURUS_CODE_TABS-->

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@ -3,24 +3,40 @@ id: functions
title: Functions
---
Writing code is fun as long as it doesn't get out of hand. To make sure our code doesn't turn into spaghetti we can group some logic into functions.
Writing code is fun as long as it does not get out of hand. To make
sure our code does not turn into spaghetti, we can structure some
logic into functions.
## Instruction blocks
## Blocks
With `block`(s) you can wrap *instructions* and *expressions* into an isolated scope.
Each `block` needs to include at least one `instruction`, or a *placeholder* instruction called `skip`.
In PascaLIGO, *blocks* enable the sequential composition of
*instructions* into an isolated scope. Each `block` needs to include
at least one instruction. If we need a placeholder *placeholder*, we
use the instruction called `skip`, that leaves the state
invariant. The rationale for `skip` instead of a truly empty block is
that it prevents you from writing an empty block by mistake.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo skip
// shorthand syntax
// terse style
block { a := a + 1 }
// verbose syntax
// verbose style
begin
a := a + 1
end
```
Blocks are more versatile than simply containing instructions:
they can also include *declarations* of values, like so:
```pascaligo skip
// terse style
block { const a : int = 1; }
// verbose style
begin
const a : int = 1;
end
```
<!--END_DOCUSAURUS_CODE_TABS-->
@ -32,54 +48,71 @@ end
Functions in PascaLIGO are defined using the `function` keyword
followed by their `name`, `parameters` and `return` type definitions.
Here's how you define a basic function that accepts two `int`s and
returns a single `int`:
Here is how you define a basic function that computes the sum of two
integers:
```pascaligo group=a
function add (const a : int; const b : int) : int is
begin
const result: int = a + b;
end with result;
block {
const sum : int = a + b
} with sum
```
The function body consists of two parts:
- `block {<code>}` - logic of the function
- `with <value>` - the return value of the function
- `block { <instructions and declarations> }` - logic of the function
- `with <value>` - the value returned by the function
#### Blockless functions
Functions that can contain all of their logic into a single
instruction/expression, can be defined without the surrounding
`block`. Instead, you can inline the necessary logic directly, like
this:
Functions that can contain all of their logic into a single expression
can be defined without a block. Instead of a block, you put an
expression, whose value is implicitly returned by the function, like
so:
```pascaligo group=b
function add (const a: int; const b : int) : int is a + b
```
You can call the function `add` defined above using the LIGO compiler
like this:
```shell
ligo run-function gitlab-pages/docs/language-basics/src/functions/blockless.ligo add '(1,2)'
# Outputs: 3
```
<!--CameLIGO-->
Functions in CameLIGO are defined using the `let` keyword, like value
bindings. The difference is that after the value name a list of
function parameters is provided, along with a return type.
Functions in CameLIGO are defined using the `let` keyword, like other
values. The difference is that a succession of parameters is provided
after the value name, followed by the return type. This follows OCaml
syntax. For example:
```cameligo group=c
let add (a : int) (b : int) : int = a + b
```
You can call the function `add` defined above using the LIGO compiler
like this:
```shell
ligo run-function gitlab-pages/docs/language-basics/src/functions/blockless.mligo add '(1,2)'
# Outputs: 3
```
CameLIGO is a little different from other syntaxes when it comes to
function parameters. In OCaml, functions can only take one
parameter. To get functions with multiple arguments like we are used
to in traditional programming languages, a technique called
to in imperative programming languages, a technique called
[currying](https://en.wikipedia.org/wiki/Currying) is used. Currying
essentially translates a function with multiple arguments into a
series of single argument functions, each returning a new function
accepting the next argument until every parameter is filled. This is
useful because it means that CameLIGO can support
useful because it means that CameLIGO supports
[partial application](https://en.wikipedia.org/wiki/Partial_application).
Currying is however *not* the preferred way to pass function arguments
in CameLIGO. While this approach is faithful to the original OCaml,
it's costlier in Michelson than naive function execution accepting
multiple arguments. Instead for most functions with more than one
parameter we should place the arguments in a
it is costlier in Michelson than naive function execution accepting
multiple arguments. Instead, for most functions with more than one
parameter, we should gather the arguments in a
[tuple](language-basics/sets-lists-tuples.md) and pass the tuple in as
a single parameter.
@ -87,56 +120,88 @@ Here is how you define a basic function that accepts two `ints` and
returns an `int` as well:
```cameligo group=b
let add (a,b: int * int) : int = a + b
let add_curry (a: int) (b: int) : int = a + b
let add (a, b : int * int) : int = a + b // Uncurried
let add_curry (a : int) (b : int) : int = add (a, b) // Curried
let increment (b : int) : int = add_curry 1 // Partial application
```
The function body is a series of expressions, which are evaluated to
give the return value.
You can run the `increment` function defined above using the LIGO
compiler like this:
```shell
ligo run-function gitlab-pages/docs/language-basics/src/functions/curry.mligo increment 5
# Outputs: 6
```
The function body is a single expression, whose value is returned.
<!--ReasonLIGO-->
Functions in ReasonLIGO are defined using the `let` keyword, like
value bindings. The difference is that after the value name a list of
function parameters is provided, along with a return type.
Here is how you define a basic function that accepts two `int`s and
returns an `int` as well:
other values. The difference is that a succession of parameters is
provided after the value name, followed by the return type.
Here is how you define a basic function that sums two integers:
```reasonligo group=b
let add = ((a, b): (int, int)) : int => a + b;
```
The function body is a series of expressions, which are evaluated to
give the return value.
You can call the function `add` defined above using the LIGO compiler
like this:
```shell
ligo run-function gitlab-pages/docs/language-basics/src/functions/blockless.religo add '(1,2)'
# Outputs: 3
```
The function body is a single expression, whose value is returned.
<!--END_DOCUSAURUS_CODE_TABS-->
## Anonymous functions
## Anonymous functions (a.k.a. lambdas)
Functions without a name, also known as anonymous functions are useful
in cases when you want to pass the function as an argument or assign
it to a key in a record or a map.
It is possible to define functions without assigning them a name. They
are useful when you want to pass them as arguments, or assign them to
a key in a record or a map.
Here is how to define an anonymous function:
Here's how to define an anonymous function assigned to a variable
`increment`, with it is appropriate function type signature.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=c
const increment : int -> int = function (const i : int) : int is i + 1;
// a = 2
const a: int = increment (1);
function increment (const b : int) : int is
(function (const a : int) : int is a + 1) (b)
const a : int = increment (1); // a = 2
```
You can check the value of `a` defined above using the LIGO compiler
like this:
```shell
ligo evaluate-value gitlab-pages/docs/language-basics/src/functions/anon.ligo a
# Outputs: 2
```
<!--CameLIGO-->
```cameligo group=c
let increment : int -> int = fun (i: int) -> i + 1
let increment (b : int) : int = (fun (a : int) -> a + 1) b
let a : int = increment 1 // a = 2
```
You can check the value of `a` defined above using the LIGO compiler
like this:
```shell
ligo evaluate-value gitlab-pages/docs/language-basics/src/functions/anon.mligo a
# Outputs: 2
```
<!--ReasonLIGO-->
```reasonligo group=c
let increment: (int => int) = (i: int) => i + 1;
let increment = (b : int) : int => ((a : int) : int => a + 1)(b);
let a : int = increment (1); // a = 2
```
You can check the value of `a` defined above using the LIGO compiler
like this:
```shell
ligo evaluate-value gitlab-pages/docs/language-basics/src/functions/anon.religo a
# Outputs: 2
```
<!--END_DOCUSAURUS_CODE_TABS-->

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@ -3,108 +3,229 @@ id: loops
title: Loops
---
## While Loop
## General Iteration
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
The PascaLIGO while loop should look familiar to users of imperative languages.
While loops are of the form `while <condition clause> <block>`, and evaluate
their associated block until the condition evaluates to false.
General iteration in PascaLIGO takes the shape of "while" loops, which
should be familiar to programmers of imperative languages. Those loops
are of the form `while <condition> <block>`. Their associated block is
repeatedly evaluated until the condition becomes true, or never
evaluated if the condition is false at the start. The loop never
terminates if the condition never becomes true. Because we are writing
smart contracts on Tezos, when the condition of a "while" loops fails
to become true, the execution will run out of gas and stop with a
failure anyway.
> ⚠️ The current PascaLIGO while loop has semantics that have diverged from other LIGO syntaxes. The goal of LIGO is that the various syntaxes express the same semantics, so this will be corrected in future versions. For details on how loops will likely work after refactoring, see the CameLIGO tab of this example.
Here is how to compute the greatest common divisors of two natural
number by means of Euclid's algorithm:
```pascaligo
function while_sum (var n : nat) : nat is block {
var i : nat := 0n ;
var r : nat := 0n ;
while i < n block {
i := i + 1n;
r := r + i;
```pascaligo group=a
function gcd (var x : nat; var y : nat) : nat is block {
if x < y then
block {
const z : nat = x;
x := y; y := z
}
} with r
else skip;
var r : nat := 0n;
while y =/= 0n block {
r := x mod y;
x := y;
y := r
}
} with x
```
You can call the function `gcd` defined above using the LIGO compiler
like so:
```shell
ligo run-function
gitlab-pages/docs/language-basics/src/loops/gcd.ligo gcd '(2n*2n*3n*11n, 2n*2n*2n*3n*3n*5n*7n)'
# Outputs: +12
```
<!--CameLIGO-->
`Loop.fold_while` is a fold operation that takes an initial value of a certain type
and then iterates on it until a condition is reached. The auxillary function
that does the fold returns either boolean true or boolean false to indicate
whether the fold should continue or not. The initial value must match the input
parameter of the auxillary function, and the auxillary should return type `(bool * input)`.
CameLIGO is a functional language where user-defined values are
constant, therefore it makes no sense in CameLIGO to feature loops,
which we understand as syntactic constructs where the state of a
stopping condition is mutated, as with "while" loops in PascaLIGO.
`continue` and `stop` are provided as syntactic sugar for the return values.
Instead, CameLIGO features a *fold operation* as a predefined function
named `Loop.fold_while`. It takes an initial value of a certain type,
called an *accumulator*, and repeatedly calls a given function, called
*iterated function*, that takes that accumulator and returns the next
value of the accumulator, until a condition is met and the fold stops
with the final value of the accumulator. The iterated function needs
to have a special type: if the type of the accumulator is `t`, then it
must have the type `bool * t` (not simply `t`). It is the boolean
value that denotes whether the stopping condition has been reached.
```cameligo
let aux (i: int) : bool * int =
if i < 100 then continue (i + 1) else stop i
```cameligo group=b
let iter (x,y : nat * nat) : bool * (nat * nat) =
if y = 0n then false, (x,y) else true, (y, x mod y)
let counter_simple (n: int) : int =
Loop.fold_while aux n
let gcd (x,y : nat * nat) : nat =
let x,y = if x < y then y,x else x,y in
let x,y = Loop.fold_while iter (x,y)
in x
```
To ease the writing and reading of the iterated functions (here,
`iter`), two predefined functions are provided: `continue` and `stop`:
```cameligo group=c
let iter (x,y : nat * nat) : bool * (nat * nat) =
if y = 0n then stop (x,y) else continue (y, x mod y)
let gcd (x,y : nat * nat) : nat =
let x,y = if x < y then y,x else x,y in
let x,y = Loop.fold_while iter (x,y)
in x
```
You can call the function `gcd` defined above using the LIGO compiler
like so:
```shell
ligo run-function
gitlab-pages/docs/language-basics/src/loops/gcd.mligo gcd (2n*2n*3n*11n, 2n*2n*2n*3n*3n*5n*7n)'
# Outputs: +12
```
<!--ReasonLIGO-->
`Loop.fold_while` is a fold operation that takes an initial value of a certain type
and then iterates on it until a condition is reached. The auxillary function
that does the fold returns either boolean true or boolean false to indicate
whether the fold should continue or not. The initial value must match the input
parameter of the auxillary function, and the auxillary should return type `(bool, input)`.
ReasonLIGO is a functional language where user-defined values are
constant, therefore it makes no sense in ReasonLIGO to feature loops,
which we understand as syntactic constructs where the state of a
stopping condition is mutated, as with "while" loops in PascaLIGO.
`continue` and `stop` are provided as syntactic sugar for the return values.
Instead, ReasonLIGO features a *fold operation* as a predefined
function named `Loop.fold_while`. It takes an initial value of a
certain type, called an *accumulator*, and repeatedly calls a given
function, called *iterated function*, that takes that accumulator and
returns the next value of the accumulator, until a condition is met
and the fold stops with the final value of the accumulator. The
iterated function needs to have a special type: if the type of the
accumulator is `t`, then it must have the type `bool * t` (not simply
`t`). It is the boolean value that denotes whether the stopping
condition has been reached.
```reasonligo
let aux = (i: int): (bool, int) =>
if (i < 100) {
continue(i + 1);
} else {
stop(i);
};
```reasonligo group=d
let iter = ((x,y) : (nat, nat)) : (bool, (nat, nat)) =>
if (y == 0n) { (false, (x,y)); } else { (true, (y, x mod y)); };
let counter_simple = (n: int): int => Loop.fold_while(aux, n);
let gcd = ((x,y) : (nat, nat)) : nat =>
let (x,y) = if (x < y) { (y,x); } else { (x,y); };
let (x,y) = Loop.fold_while (iter, (x,y));
x;
```
To ease the writing and reading of the iterated functions (here,
`iter`), two predefined functions are provided: `continue` and `stop`:
```reasonligo group=e
let iter = ((x,y) : (nat, nat)) : (bool, (nat, nat)) =>
if (y == 0n) { stop ((x,y)); } else { continue ((y, x mod y)); };
let gcd = ((x,y) : (nat, nat)) : nat =>
let (x,y) = if (x < y) { (y,x); } else { (x,y); };
let (x,y) = Loop.fold_while (iter, (x,y));
x;
```
<!--END_DOCUSAURUS_CODE_TABS-->
## For Loop
## For Loops
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
To iterate over a range of integers you use a loop of the form `for <variable assignment> to <integer> <block>`.
To iterate over a range of integers you use a loop of the form `for
<variable assignment> to <upper integer bound> <block>`, which is
familiar for programmers of imperative languages. Note that, for the
sake of generality, the bounds are of type `int`, not `nat`.
```pascaligo
function for_sum (var n : nat) : int is block {
```pascaligo group=f
function sum (var n : nat) : int is block {
var acc : int := 0;
for i := 1 to int(n)
begin
acc := acc + i;
end
for i := 1 to int (n) block {
acc := acc + i
}
} with acc
```
You can call the function `sum` defined above using the LIGO compiler
like so:
```shell
ligo run-function
gitlab-pages/docs/language-basics/src/loops/sum.ligo sum 7n
# Outputs: 28
```
<!--END_DOCUSAURUS_CODE_TABS-->
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
PascaLIGO for loops can also iterate through the contents of a collection. This is
done with a loop of the form `for <element var> in <collection type> <collection var> <block>`.
PascaLIGO "for" loops can also iterate through the contents of a
collection, that is, a list, a set or a map. This is done with a loop
of the form `for <element var> in <collection type> <collection var>
<block>`, where `<collection type` is any of the following keywords:
`list`, `set` or `map`.
```pascaligo
function for_collection_list (var nee : unit) : (int * string) is block {
var acc : int := 0;
var st : string := "to";
var mylist : list(int) := list 1; 1; 1 end;
for x in list mylist
begin
acc := acc + x;
st := st ^ "to";
end
} with (acc, st)
Here is an example where the integers in a list are summed up.
```pascaligo group=g
function sum_list (var l : list (int)) : int is block {
var total : int := 0;
for i in list l block {
total := total + i
}
} with total
```
You can call the function `sum_list` defined above using the LIGO compiler
like so:
```shell
ligo run-function
gitlab-pages/docs/language-basics/src/loops/collection.ligo sum_list
'list [1;2;3]'
# Outputs: 6
```
Here is an example where the integers in a set are summed up.
```pascaligo=g
function sum_set (var s : set (int)) : int is block {
var total : int := 0;
for i in set s block {
total := total + i
}
} with total
```
You can call the function `sum_set` defined above using the LIGO compiler
like so:
```shell
ligo run-function
gitlab-pages/docs/language-basics/src/loops/collection.ligo sum_set
'set [1;2;3]'
# Outputs: 6
```
Loops over maps are actually loops over the bindings of the map, that
is, a pair key-value noted `key -> value` (or any other
variables). Give a map from strings to integers, here is how to sum
all the integers and concatenate all the strings.
You can call the function `sum_map` defined above using the LIGO compiler
like so:
```shell
ligo run-function
gitlab-pages/docs/language-basics/src/loops/collection.ligo sum_map
'map ["1"->1; "2"->2; "3"->3]'
# Outputs: ( "123", 6 )
```
<!--END_DOCUSAURUS_CODE_TABS-->

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@ -7,119 +7,155 @@ LIGO offers three built-in numerical types: `int`, `nat` and `tez`.
## Addition
Addition in ligo is acomplished by using the `+` operator. Some type constraints apply; for example you can't add `tez + nat`.
Addition in LIGO is accomplished by means of the `+` infix
operator. Some type constraints apply, for example you ca not add a
value of type `tez` to a value of type `nat`.
In the following example you can find a series of arithmetic operations, including various numerical types. However, some bits of the example won't compile because adding an `int` to a `nat` produces an `int`, not a `nat`. Similiar rules apply for `tez`:
In the following example you can find a series of arithmetic
operations, including various numerical types. However, some bits
remain in comments because they would otherwise not compile because,
for example, adding a value of type `int` to a value of type `tez` is
invalid. Note that adding an integer to a natural number produces an
integer.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=a
// int + int produces int
const a: int = 5 + 10;
// nat + int produces int
const b: int = 5n + 10;
// tez + tez produces tez
const c: tez = 5mutez + 10mutez;
// you can't add tez + int or tez + nat, this won't compile
// const d: tez = 5mutez + 10n;
// two nats produce a nat
const e: nat = 5n + 10n;
// nat + int produces an int, this won't compile
// int + int yields int
const a : int = 5 + 10
// nat + int yields int
const b : int = 5n + 10
// tez + tez yields tez
const c : tez = 5mutez + 10mutez
//tez + int or tez + nat is invalid
// const d : tez = 5mutez + 10n
// two nats yield a nat
const e : nat = 5n + 10n
// nat + int yields an int: invalid
// const f : nat = 5n + 10;
const g: int = 1_000_000;
const g : int = 1_000_000
```
> Pro tip: you can use underscores for readability when defining large numbers
> Pro tip: you can use underscores for readability when defining large
> numbers:
>
>```pascaligo
>const g: int = 1_000_000;
> const sum : tez = 100_000mutez
>```
<!--CameLIGO-->
```cameligo group=a
// int + int produces int
// int + int yields int
let a : int = 5 + 10
// nat + int produces int
// nat + int yields int
let b : int = 5n + 10
// tez + tez produces tez
// tez + tez yields tez
let c : tez = 5mutez + 10mutez
// you can't add tez + int or tez + nat, this won't compile
// tez + int or tez + nat is invalid
// const d : tez = 5mutez + 10n
// two nats produce a nat
// two nats yield a nat
let e : nat = 5n + 10n
// nat + int produces an int, this won't compile
// nat + int yields an int: invalid
// const f : nat = 5n + 10
let g : int = 1_000_000
```
> Pro tip: you can use underscores for readability when defining large numbers
> Pro tip: you can use underscores for readability when defining large
> numbers:
>
>```cameligo
>let g: int = 1_000_000;
>let sum : tez = 100_000mutez
>```
<!--ReasonLIGO-->
```reasonligo group=a
(* int + int produces int *)
// int + int yields int
let a : int = 5 + 10;
(* nat + int produces int *)
// nat + int yields int
let b : int = 5n + 10;
(* tez + tez produces tez *)
// tez + tez yields tez
let c : tez = 5mutez + 10mutez;
(* you can't add tez + int or tez + nat, this won't compile:
let d: tez = 5mutez + 10n; *)
(* two nats produce a nat *)
// tez + int or tez + nat is invalid:
// let d : tez = 5mutez + 10n;
// two nats yield a nat
let e : nat = 5n + 10n;
(* nat + int produces an int, this won't compile:
let f: nat = 5n + 10; *)
// nat + int yields an int: invalid
//let f : nat = 5n + 10;
let g : int = 1_000_000;
```
> Pro tip: you can use underscores for readability when defining large numbers
>
> Pro tip: you can use underscores for readability when defining large
> numbers:
>```reasonligo
>let g: int = 1_000_000;
>let sum : tex = 100_000mutez;
>```
<!--END_DOCUSAURUS_CODE_TABS-->
## Subtraction
The simpliest substraction looks like this:
Subtraction looks like as follows.
> ⚠️ Even when subtracting two `nats`, the result is an `int`
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=b
const a: int = 5 - 10;
// substraction of two nats, yields an int
const b: int = 5n - 2n;
// won't compile, result is an int, not a nat
// const c: nat = 5n - 2n;
const d: tez = 5mutez - 1mutez;
const a : int = 5 - 10
// Subtraction of two nats yields an int
const b : int = 5n - 2n
// Therefore the following is invalid
// const c : nat = 5n - 2n
const d : tez = 5mutez - 1mutez
```
<!--CameLIGO-->
```cameligo group=b
let a : int = 5 - 10
// substraction of two nats, yields an int
// Subtraction of two nats yields an int
let b : int = 5n - 2n
// won't compile, result is an int, not a nat
// Therefore the following is invalid
// const c : nat = 5n - 2n
let d : tez = 5mutez - 1mutez
```
<!--ReasonLIGO-->
```reasonligo group=b
let a : int = 5 - 10;
(* substraction of two nats, yields an int *)
// Subtraction of two nats yields an int
let b : int = 5n - 2n;
(* won't compile, result is an int, not a nat *)
(* let c: nat = 5n - 2n; *)
// Therefore the following is invalid
// let c : nat = 5n - 2n;
let d : tez = 5mutez - 1mutez;
```
@ -134,9 +170,9 @@ You can multiply values of the same type, such as:
<!--Pascaligo-->
```pascaligo group=c
const a: int = 5 * 5;
const b: nat = 5n * 5n;
// you can also multiply `nat` and `tez`
const a : int = 5 * 5
const b : nat = 5n * 5n
// You can also multiply `nat` and `tez` in any order
const c : tez = 5n * 5mutez;
```
@ -144,7 +180,7 @@ const c: tez = 5n * 5mutez;
```cameligo group=c
let a : int = 5 * 5
let b : nat = 5n * 5n
// you can also multiply `nat` and `tez`
// You can also multiply `nat` and `tez` in any order
let c : tez = 5n * 5mutez
```
@ -152,25 +188,24 @@ let c: tez = 5n * 5mutez
```reasonligo group=c
let a : int = 5 * 5;
let b : nat = 5n * 5n;
(* you can also multiply `nat` and `tez` *)
// You can also multiply `nat` and `tez` in any order
let c : tez = 5n * 5mutez;
```
<!--END_DOCUSAURUS_CODE_TABS-->
## Division
In LIGO you can divide `int`, `nat`, and `tez`. Here's how:
In LIGO you can divide `int`, `nat`, and `tez`. Here is how:
> ⚠️ Division of two `tez` values results into a `nat`
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=d
const a: int = 10 / 3;
const b: nat = 10n / 3n;
const c: nat = 10mutez / 3mutez;
const a : int = 10 / 3
const b : nat = 10n / 3n
const c : nat = 10mutez / 3mutez
```
<!--CameLIGO-->
@ -191,25 +226,19 @@ let c: nat = 10mutez / 3mutez;
## From `int` to `nat` and back
You can *cast* an `int` to a `nat` and vice versa, here's how:
You can *cast* an `int` to a `nat` and vice versa. Here is how:
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
<!--PascaLIGO-->
```pascaligo group=e
const a: int = int(1n);
const b: nat = abs(1);
const a : int = int (1n)
const b : nat = abs (1)
```
<!--END_DOCUSAURUS_CODE_TABS-->
## Check if a value is a `nat`
You can check if a value is a `nat`, by using a syntax specific built-in function, which accepts an `int` and returns an `option(nat)`, more specifically `Some(nat)` if the provided integer is a natural number, and `None` otherwise:
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo
const its_a_nat: option(nat) = is_nat(1)
<!--CameLIGO-->
```cameligo group=e
let a : int = int (1n)
let b : nat = abs (1)
```
<!--ReasonLIGO-->
@ -219,3 +248,28 @@ let b: nat = abs(1);
```
<!--END_DOCUSAURUS_CODE_TABS-->
## Check if a value is a `nat`
You can check if a value is a `nat` by using a syntax specific
built-in function, which accepts an `int` and returns an optional
`nat`: if `Some(nat)` then the provided integer was indeed a natural
number, and not otherwise.
<!--DOCUSAURUS_CODE_TABS-->
<!--PascaLIGO-->
```pascaligo group=e
const is_a_nat : option (nat) = is_nat (1)
```
<!--CameLIGO-->
```cameligo group=e
let is_a_nat : nat option = Michelson.is_nat (1)
```
<!--ReasonLIGO-->
```reasonligo group=e
let is_a_nat : option (nat) = Michelson.is_nat (1);
```
<!--END_DOCUSAURUS_CODE_TABS-->

660
gitlab-pages/docs/language-basics/sets-lists-tuples.md
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@ -1,85 +1,378 @@
---
id: sets-lists-tuples
title: Sets, Lists, Tuples
title: Tuples, Lists, Sets
---
Apart from complex data types such as `maps` and `records`, ligo also
exposes `sets`, `lists` and `tuples`.
exposes `tuples`, `lists` and `sets`.
> ⚠️ Make sure to pick the appropriate data type for your use case, and
> bear in mind the related gas costs.
## Tuples
Tuples gather a given number of values in a specific order and those
values, called *components*, can be retrieved by their index
(position). Probably the most common tuple is the *pair*. For
example, if we were storing coordinates on a two dimensional grid we
might use a pair of type `int * int` to store the coordinates `x` and
`y` as the pair value `(x,y)`. There is a *specific order*, so `(y,x)`
is not equal to `(x,y)`. The number of components is part of the type
of a tuple, so, for example, we cannot add an extra component to a
pair and obtain a triple of the same type: `(x,y)` has always a
different type from `(x,y,z)`, whereas `(y,x)` may have the same type.
Like records, tuple components can be of arbitrary types.
### Defining a tuple
Unlike [a record](language-basics/maps-records.md), tuple types do not
have to be defined before they can be used. However below we will give
them names by *type aliasing*.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=c
type full_name is string * string // Alias
const full_name : full_name = ("Alice", "Johnson")
```
<!--CameLIGO-->
```cameligo group=c
type full_name = string * string // Alias
(* The parenthesis here are optional *)
let full_name : full_name = ("Alice", "Johnson")
```
<!--ReasonLIGO-->
```reasonligo group=c
type full_name = (string, string); // Alias
(* The parenthesis here are optional *)
let full_name : full_name = ("Alice", "Johnson");
```
<!--END_DOCUSAURUS_CODE_TABS-->
### Accessing an Element in a Tuple
Accessing the components of a tuple in OCaml is achieved by
[pattern matching](language-basics/unit-option-pattern-matching.md). LIGO
currently supports tuple patterns only in the parameters of functions,
not in pattern matching. In LIGO, however, we can access components by
their position in their tuple, which cannot be done in OCaml.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
Tuple components are one-indexed like so:
```pascaligo group=c
const first_name : string = full_name.1;
```
<!--Cameligo-->
Tuple elements are zero-indexed and accessed like so:
```cameligo group=c
let first_name : string = full_name.0
```
<!--ReasonLIGO-->
Tuple components are one-indexed like so:
```reasonligo group=c
let first_name : string = full_name[1];
```
## Lists
Lists are linear collections of elements of the same type. Linear
means that, in order to reach an element in a list, we must visit all
the elements before (sequential access). Elements can be repeated, as
only their order in the collection matters. The first element is
called the *head*, and the sub-list after the head is called the
*tail*. For those familiar with algorithmic data structure, you can
think of a list a *stack*, where the top is written on the left.
> 💡 Lists are useful when returning operations from a smart
> contract's entrypoint.
### Defining a List
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=b
const my_list : list (int) = list [1; 2; 2] // The head is 1
```
<!--CameLIGO-->
```cameligo group=b
let my_list : int list = [1; 2; 2] // The head is 1
```
<!--ReasonLIGO-->
```reasonligo group=b
let my_list : list (int) = [1, 2, 2]; // The head is 1
```
<!--END_DOCUSAURUS_CODE_TABS-->
### Adding to a List
<!--DOCUSAURUS_CODE_TABS-->
Lists can be augmented by adding an element before the head (or, in
terms of stack, by *pushing an element on top*). This operation is
usually called *consing* in functional languages.
<!--Pascaligo-->
In PascaLIGO, the *cons operator* is infix and noted `#`. It is not
symmetric: on the left lies the element to cons, and, on the right, a
list on which to cons. (The symbol is helpfully asymmetric to remind
you of that.)
```pascaligo group=b
const larger_list : list (int) = 5 # my_list
```
<!--CameLIGO-->
In CameLIGO, the *cons operator* is infix and noted `::`. It is not
symmetric: on the left lies the element to cons, and, on the right, a
list on which to cons.
```cameligo group=b
let larger_list : int list = 5 :: my_list
```
<!--ReasonLIGO-->
In ReasonLIGO, the *cons operator* is infix and noted `, ...`. It is
not symmetric: on the left lies the element to cons, and, on the
right, a list on which to cons.
```reasonligo group=b
let larger_list : list (int) = [5, ...my_list];
```
<!--END_DOCUSAURUS_CODE_TABS-->
<br/>
> 💡 Lists can be iterated, folded or mapped to different values. You
> can find additional examples
> [here](https://gitlab.com/ligolang/ligo/tree/dev/src/test/contracts)
> and other built-in operators
> [here](https://gitlab.com/ligolang/ligo/blob/dev/src/passes/operators/operators.ml#L59)
### Mapping of a List
We may want to apply a function to all the elements of a list and
obtain the resulting list, in the same order. For example, we may want
to create a list that contains all the elements of another list
incremented by one. This is a special case of *fold operation* called
a *map operation*. Map operations (not to be confused by the
[map data structure](language-basics/maps-records.md)), are predefined
functions in LIGO. They take as a parameter the function to apply to
all the elements. Of course, that function must return a value of the
same type as the element.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
In PascaLIGO, the map function is called `list_map`.
```pascaligo group=b
function increment (const i : int): int is i + 1
// Creates a new list with all elements incremented by 1
const plus_one : list (int) = list_map (increment, larger_list)
```
<!--CameLIGO-->
In CameLIGO, the map function is called `List.map`.
```cameligo group=b
let increment (i : int) : int = i + 1
// Creates a new list with all elements incremented by 1
let plus_one : int list = List.map increment larger_list
```
<!--ReasonLIGO-->
In CameLIGO, the map function is called `List.map`.
```reasonligo group=b
let increment = (i : int) : int => i + 1;
// Creates a new list with all elements incremented by 1
let plus_one : list (int) = List.map (increment, larger_list);
```
<!--END_DOCUSAURUS_CODE_TABS-->
### Folding of over a List
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=b
function sum (const acc : int; const i : int): int is acc + i
const sum_of_elements : int = list_fold (sum, my_list, 0)
```
<!--CameLIGO-->
```cameligo group=b
let sum (acc, i: int * int) : int = acc + i
let sum_of_elements : int = List.fold sum my_list 0
```
<!--ReasonLIGO-->
```reasonligo group=b
let sum = ((result, i): (int, int)): int => result + i;
let sum_of_elements : int = List.fold (sum, my_list, 0);
```
<!--END_DOCUSAURUS_CODE_TABS-->
> ⚠️ Make sure to pick the appropriate data type for your use case; it carries not only semantic but also gas related costs.
## Sets
Sets are similar to lists. The main difference is that elements of a
`set` must be *unique*.
Sets are unordered collections of values of the same type, like lists
are ordered collections. Like the mathematical sets and lists, sets
can be empty and, if not, elements of sets in LIGO are *unique*,
whereas they can be repeated in a list.
### Defining a set
### Empty Sets
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=a
type int_set is set (int);
const my_set : int_set = set 1; 2; 3 end
const my_set : set (int) = set []
```
<!--CameLIGO-->
```cameligo group=a
let my_set : int set = (Set.empty : int set)
```
<!--ReasonLIGO-->
```reasonligo group=a
let my_set : set (int) = (Set.empty : set (int));
```
<!--END_DOCUSAURUS_CODE_TABS-->
### Non-empty Sets
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
In PascaLIGO, the notation for sets is similar to that for lists,
except the keyword `set` is used before:
```pascaligo group=a
const my_set : set (int) = set [3; 2; 2; 1]
```
You can check that `2` is not repeated in `my_set` by using the LIGO
compiler like this (the output will sort the elements of the set, but
that order is not significant for the compiler):
```shell
ligo evaluate-value
gitlab-pages/docs/language-basics/src/sets-lists-tuples/sets.ligo my_set
# Outputs: { 3 ; 2 ; 1 }
```
<!--CameLIGO-->
In CameLIGO, there is no predefined syntactic construct for sets: you
must build your set by adding to the empty set. (This is the way in
OCaml.)
```cameligo group=a
type int_set = int set
let my_set : int_set =
Set.add 3 (Set.add 2 (Set.add 1 (Set.empty: int set)))
let my_set : int set =
Set.add 3 (Set.add 2 (Set.add 2 (Set.add 1 (Set.empty : int set))))
```
You can check that `2` is not repeated in `my_set` by using the LIGO
compiler like this (the output will sort the elements of the set, but
that order is not significant for the compiler):
```shell
ligo evaluate-value
gitlab-pages/docs/language-basics/src/sets-lists-tuples/sets.mligo my_set
# Outputs: { 3 ; 2 ; 1 }
```
<!--ReasonLIGO-->
In ReasonLIGO, there is no predefined syntactic construct for sets:
you must build your set by adding to the empty set. (This is the way
in OCaml.)
```reasonligo group=a
type int_set = set (int);
let my_set : int_set =
Set.add (3, Set.add (2, Set.add (1, Set.empty: set (int))));
let my_set : set (int) =
Set.add (3, Set.add (2, Set.add (2, Set.add (1, Set.empty : set (int)))));
```
You can check that `2` is not repeated in `my_set` by using the LIGO
compiler like this (the output will sort the elements of the set, but
that order is not significant for the compiler):
```shell
ligo evaluate-value
gitlab-pages/docs/language-basics/src/sets-lists-tuples/sets.religo my_set
# Outputs: { 3 ; 2 ; 1 }
```
<!--END_DOCUSAURUS_CODE_TABS-->
### Empty sets
### Set Membership
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=a
const my_set: int_set = set end
const my_set_2: int_set = set_empty
```
<!--CameLIGO-->
```cameligo group=a
let my_set: int_set = (Set.empty: int set)
```
<!--ReasonLIGO-->
```reasonligo group=a
let my_set: int_set = (Set.empty: set (int));
```
<!--END_DOCUSAURUS_CODE_TABS-->
### Checking if set contains an element
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
PascaLIGO features a special keyword `constains` that operates like an
infix operator checking membership in a set.
```pascaligo group=a
const contains_three : bool = my_set contains 3
// or alternatively
const contains_three_fn: bool = set_mem (3, my_set);
const contains_3 : bool = my_set contains 3
```
<!--CameLIGO-->
```cameligo group=a
let contains_three: bool = Set.mem 3 my_set
let contains_3 : bool = Set.mem 3 my_set
```
<!--ReasonLIGO-->
```reasonligo group=a
let contains_three: bool = Set.mem(3, my_set);
let contains_3 : bool = Set.mem (3, my_set);
```
<!--END_DOCUSAURUS_CODE_TABS-->
### Obtaining the size of a set
### Cardinal
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=a
const set_size : nat = size (my_set)
@ -98,245 +391,116 @@ let set_size: nat = Set.size (my_set);
<!--END_DOCUSAURUS_CODE_TABS-->
### Modifying a set
### Adding or Removing from a Set
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
In PascaLIGO, there are two ways to update a set. Either we create a
new set from the given one, or we modify it in-place. First, let us
consider the former:
```pascaligo group=a
const larger_set: int_set = set_add(4, my_set);
const smaller_set: int_set = set_remove(3, my_set);
const larger_set : set (int) = set_add (4, my_set)
const smaller_set : set (int) = set_remove (3, my_set)
```
If we are in a block, we can use an instruction to modify the set
bound to a given variable. This is called a *patch*. It is only
possible to add elements by means of a patch, not remove any: it is
the union of two sets.
In the following example, the parameter set `s` of function `update`
is augmented (as the `with s` shows) to include `4` and `7`, that is,
this instruction is equivalent to perform the union of two sets, one
that is modified in-place, and the other given as a literal
(extensional definition).
``pascaligo group=a
function update (var s : set (int)) : set (int) is block {
patch s with set [4; 7]
} with s
const new_set : set (int) = update (my_set)
```
<!--CameLIGO-->
In CameLIGO, we update a given set by creating another one, with or
without some elements.
```cameligo group=a
let larger_set: int_set = Set.add 4 my_set
let smaller_set: int_set = Set.remove 3 my_set
let larger_set : int set = Set.add 4 my_set
let smaller_set : int set = Set.remove 3 my_set
```
<!--ReasonLIGO-->
In ReasonLIGO, we update a given set by creating another one, with or
without some elements.
```reasonligo group=a
let larger_set: int_set = Set.add(4, my_set);
let smaller_set: int_set = Set.remove(3, my_set);
let larger_set : set (int) = Set.add (4, my_set);
let smaller_set : set (int) = Set.remove (3, my_set);
```
<!--END_DOCUSAURUS_CODE_TABS-->
### Folding a set
### Folding over a Set
<!--DOCUSAURUS_CODE_TABS-->
Given a set, we may want to apply a function in turn to all the
elements it contains, while accumulating some value which is returned
at the end. This is a *fold operation*. In the following example, we
sum up all the elements of the set `my_set` defined above.
<!--Pascaligo-->
In PascaLIGO, the folded function takes the accumulator first and the
(current) set element second. The predefined fold is called `set_fold`.
```pascaligo group=a
function sum(const result: int; const i: int): int is result + i;
// Outputs 6
const sum_of_a_set: int = set_fold(sum, my_set, 0);
function sum (const acc : int; const i : int): int is acc + i
const sum_of_elements : int = set_fold (sum, my_set, 0)
```
It is possible to use a *loop* over a set as well.
```pascaligo group=a
function loop (const s : set (int)) : int is block {
var sum : int := 0;
for element in set s block {
sum := sum + element
}
} with sum
```
<!--CameLIGO-->
In CameLIGO, the predefined fold over sets is called `Set.fold`.
```cameligo group=a
let sum (result, i: int * int) : int = result + i
let sum_of_a_set: int = Set.fold sum my_set 0
let sum (acc, i : int * int) : int = acc + i
let sum_of_elements : int = Set.fold sum my_set 0
```
<!--ReasonLIGO-->
```reasonligo group=a
let sum = (result_i: (int, int)): int => result_i[0] + result_i[1];
let sum_of_a_set: int = Set.fold(sum, my_set, 0);
`
In ReasonLIGO, the predefined fold over sets is called `Set.fold`.
``reasonligo group=a
let sum = ((acc, i) : (int, int)) : int => acc + i;
let sum_of_elements : int = Set.fold (sum, my_set, 0);
```
<!--END_DOCUSAURUS_CODE_TABS-->
## Lists
Lists are similar to sets, but their elements don't need to be unique and they don't offer the same range of built-in functions.
> 💡 Lists are useful when returning operations from a smart contract's entrypoint.
### Defining a list
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=b
type int_list is list(int);
const my_list: int_list = list
1;
2;
3;
end
```
<!--CameLIGO-->
```cameligo group=b
type int_list = int list
let my_list: int_list = [1; 2; 3]
```
<!--ReasonLIGO-->
```reasonligo group=b
type int_list = list(int);
let my_list: int_list = [1, 2, 3];
```
<!--END_DOCUSAURUS_CODE_TABS-->
### Appending an element to a list
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=b
const larger_list: int_list = cons(4, my_list);
const even_larger_list: int_list = 5 # larger_list;
```
<!--CameLIGO-->
```cameligo group=b
let larger_list: int_list = 4 :: my_list
(* CameLIGO doesn't have a List.cons *)
```
<!--ReasonLIGO-->
```reasonligo group=b
let larger_list: int_list = [4, ...my_list];
(* ReasonLIGO doesn't have a List.cons *)
```
<!--END_DOCUSAURUS_CODE_TABS-->
<br/>
> 💡 Lists can be iterated, folded or mapped to different values. You can find additional examples [here](https://gitlab.com/ligolang/ligo/tree/dev/src/test/contracts) and other built-in operators [here](https://gitlab.com/ligolang/ligo/blob/dev/src/passes/operators/operators.ml#L59)
### Mapping of a list
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=b
function increment(const i: int): int is block { skip } with i + 1;
// Creates a new list with elements incremented by 1
const incremented_list: int_list = list_map(increment, even_larger_list);
```
<!--CameLIGO-->
```cameligo group=b
let increment (i: int) : int = i + 1
(* Creates a new list with elements incremented by 1 *)
let incremented_list: int_list = List.map increment larger_list
```
<!--ReasonLIGO-->
```reasonligo group=b
let increment = (i: int): int => i + 1;
(* Creates a new list with elements incremented by 1 *)
let incremented_list: int_list = List.map(increment, larger_list);
```
<!--END_DOCUSAURUS_CODE_TABS-->
### Folding of a list:
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=b
function sum(const result: int; const i: int): int is block { skip } with result + i;
// Outputs 6
const sum_of_a_list: int = list_fold(sum, my_list, 0);
```
<!--CameLIGO-->
```cameligo group=b
let sum (result, i: int * int) : int = result + i
// Outputs 6
let sum_of_a_list: int = List.fold sum my_list 0
```
<!--ReasonLIGO-->
```reasonligo group=b
let sum = ((result, i): (int, int)): int => result + i;
(* Outputs 6 *)
let sum_of_a_list: int = List.fold(sum, my_list, 0);
```
<!--END_DOCUSAURUS_CODE_TABS-->
## Tuples
Tuples are used to store related data that has a **specific order** and **defined
length** without the need for named fields or a dedicated type identity. Probably
the most common tuple is a pair of type `(a, b)`. For example, if we were storing
coordinates on a two dimensional grid we might use a pair tuple of type `int * int`
to store the coordinates x and y. There is a **specific order** because x and y must
always stay in the same location within the tuple for the data to make sense. There is
also a **defined length** because the tuple pair can only ever have two elements,
if we added a third dimension `z` its type would be incompatible with that of the
pair tuple.
Like records, tuples can have members of arbitrary types in the same structure.
### Defining a tuple
Unlike [a record](language-basics/maps-records.md), tuple types do not have to be
defined before they can be used. However below we will give them names for the
sake of illustration.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=c
type full_name is string * string;
const full_name: full_name = ("Alice", "Johnson");
```
<!--CameLIGO-->
```cameligo group=c
type full_name = string * string
(* The parenthesis here are optional *)
let full_name: full_name = ("Alice", "Johnson")
```
<!--ReasonLIGO-->
```reasonligo group=c
type full_name = (string, string);
(* The parenthesis here are optional *)
let full_name: full_name = ("Alice", "Johnson");
```
<!--END_DOCUSAURUS_CODE_TABS-->
### Accessing an element in a tuple
The traditional way to access the elements of a tuple in OCaml is through
[a pattern match](language-basics/unit-option-pattern-matching.md). LIGO **does
not** currently support tuple patterns in its syntaxes.
However, it is possible to access LIGO tuples by their position.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
Tuple elements are one-indexed and accessed like so:
```pascaligo group=c
const first_name: string = full_name.1;
```
<!--Cameligo-->
Tuple elements are zero-indexed and accessed like so:
```cameligo group=c
let first_name: string = full_name.0
```
<!--ReasonLIGO-->
```reasonligo group=c
let first_name: string = full_name[1];
```
<!--END_DOCUSAURUS_CODE_TABS-->

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@ -0,0 +1,4 @@
type magnitude is Small | Large // See variant types
function compare (const n : nat) : magnitude is
if n < 10n then Small (Unit) else Large (Unit)

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@ -0,0 +1,4 @@
type magnitude = Small | Large // See variant types
let compare (n : nat) : magnitude =
if n < 10n then Small else Large

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@ -0,0 +1,4 @@
type magnitude = | Small | Large; // See variant types
let compare = (n : nat) : magnitude =>
if (n < 10n) { Small; } else { Large; };

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@ -1,4 +0,0 @@
const min_age: nat = 16n;
function is_adult(const age: nat): bool is
if (age > min_age) then True else False

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@ -1,4 +0,0 @@
function add(const a: int; const b: int): int is
begin
const result: int = a + b;
end with result;

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@ -1,3 +1,4 @@
const increment : (int -> int) = (function (const i : int) : int is i + 1);
// a = 2
const a: int = increment(1);
function increment (const b : int) : int is
(function (const a : int) : int is a + 1) (b)
const a : int = increment (1); // a = 2

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@ -0,0 +1,2 @@
let increment (b : int) : int = (fun (a : int) -> a + 1) b
let a : int = increment 1 // a = 2

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@ -0,0 +1,2 @@
let increment = (b : int) : int => ((a : int) : int => a + 1)(b);
let a : int = increment (1); // a = 2

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@ -0,0 +1 @@
let add (a : int) (b : int) : int = a + b

1
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@ -0,0 +1 @@
let add = ((a, b): (int, int)) : int => a + b;

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@ -0,0 +1,3 @@
let add (a, b : int * int) : int = a + b // Uncurried
let add_curry (a : int) (b : int) : int = add (a,b) // Curried
let increment (b : int) : int = add_curry 1 // Partial application

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@ -0,0 +1,22 @@
function sum_list (var l : list (int)) : int is block {
var total : int := 0;
for i in list l block {
total := total + i
}
} with total
function sum_set (var s : set (int)) : int is block {
var total : int := 0;
for i in set s block {
total := total + i
}
} with total
function sum_map (var m : map (string, int)) : string * int is block {
var string_total : string := "";
var int_total : int := 0;
for key -> value in map m block {
string_total := string_total ^ key;
int_total := int_total + value
}
} with (string_total, int_total)

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@ -0,0 +1,14 @@
function gcd (var x : nat; var y : nat) : nat is block {
if x < y then
block {
const z : nat = x;
x := y; y := z
}
else skip;
var r : nat := 0n;
while y =/= 0n block {
r := x mod y;
x := y;
y := r
}
} with x

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@ -0,0 +1,7 @@
let iter (x,y : nat * nat) : bool * (nat * nat) =
if y = 0n then stop (x,y) else continue (y, x mod y)
let gcd (x,y : nat * nat) : nat =
let x,y = if x < y then y,x else x,y in
let x,y = Loop.fold_while iter (x,y)
in x

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@ -0,0 +1,7 @@
let iter = ((x,y) : (nat, nat)) : (bool, (nat, nat)) =>
if (y == 0n) { stop ((x,y)); } else { continue ((y, x mod y)); };
let gcd = ((x,y) : (nat, nat)) : nat =>
let (x,y) = if (x < y) { (y,x); } else { (x,y); };
let (x,y) = Loop.fold_while (iter, (x,y));
x;

6
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@ -0,0 +1,6 @@
function sum (var n : nat) : int is block {
var acc : int := 0;
for i := 1 to int (n) block {
acc := acc + i
}
} with acc

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@ -0,0 +1,10 @@
type point is record [x : int; y : int; z : int]
type vector is record [dx : int; dy : int]
const origin : point = record [x = 0; y = 0; z = 0]
function xy_translate (var p : point; const vec : vector) : point is
block {
patch p with record [x = p.x + vec.dx];
patch p with record [y = p.y + vec.dy]
} with p

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@ -0,0 +1,9 @@
type point is record [x : int; y : int; z : int]
type vector is record [dx : int; dy : int]
const origin : point = record [x = 0; y = 0; z = 0]
function xy_translate (var p : point; const vec : vector) : point is
block {
patch p with record [x = p.x + vec.dx; y = p.y + vec.dy]
} with p

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@ -0,0 +1,8 @@
type point is record [x : int; y : int; z : int]
type vector is record [dx : int; dy : int]
const origin : point = record [x = 0; y = 0; z = 0]
function xy_translate (var p : point; const vec : vector) : point is block {
const p : point = p with record [x = p.x + vec.dx; y = p.y + vec.dy]
} with p

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@ -0,0 +1,7 @@
type point is record [x : int; y : int; z : int]
type vector is record [dx : int; dy : int]
const origin : point = record [x = 0; y = 0; z = 0]
function xy_translate (var p : point; const vec : vector) : point is
p with record [x = p.x + vec.dx; y = p.y + vec.dy]

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@ -0,0 +1,7 @@
type point = {x : int; y : int; z : int}
type vector = {dx : int; dy : int}
let origin : point = {x = 0; y = 0; z = 0}
let xy_translate (p, vec : point * vector) : point =
{p with x = p.x + vec.dx; y = p.y + vec.dy}

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@ -0,0 +1,7 @@
type point = {x : int, y : int, z : int};
type vector = {dx : int, dy : int};
let origin : point = {x : 0, y : 0, z : 0};
let xy_translate = ((p, vec) : (point, vector)) : point =>
{...p, x : p.x + vec.dx, y : p.y + vec.dy};

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@ -1,13 +0,0 @@
// int + int produces int
const a: int = 5 + 10;
// nat + int produces int
const b: int = 5n + 10;
// tez + tez produces tez
const c: tez = 5mutez + 10mutez;
// you can't add tez + int or tez + nat, this won't compile
// const d: tez = 5mutez + 10n;
// two nats produce a nat
const e: nat = 5n + 10n;
// nat + int produces an int, this won't compile
// const f: nat = 5n + 10;
const g: int = 1_000_000;

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@ -1,2 +0,0 @@
const a: int = int(1n);
const b: nat = abs(1);

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@ -1,5 +0,0 @@
const a: int = 10 / 3;
const b: nat = 10n / 3n;
const c: nat = 10mutez / 3mutez;
const d: int = 10 / 5 / 2 * 5;

1
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@ -1 +0,0 @@
const its_a_nat: option(nat) = is_nat(1)

3
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@ -1,3 +0,0 @@
const a: int = 5 * 5;
const b: nat = 5n * 5n;
const c: tez = 5n * 5mutez;

6
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@ -1,6 +0,0 @@
const a: int = 5 - 10;
// substraction of two nats, yields an int
const b: int = 5n - 2n;
// won't compile, result is an int, not a nat
// const c: nat = 5n - 2n;
const d: tez = 5mutez - 1mutez;

0
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@ -0,0 +1,12 @@
const my_list : list (int) = list [1; 2; 2] // The head is 1
const larger_list : int_list = 5 # my_list
function increment (const i : int): int is i + 1
// Creates a new list with all elements incremented by 1
const plus_one : list (int) = list_map (increment, larger_list);
function sum (const acc : int; const i : int): int is acc + i
const sum_of_elements : int = list_fold (sum, my_list, 0)

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@ -0,0 +1,28 @@
type int_set is set (int)
const my_set : int_set = set [3; 2; 2; 1]
const contains_3 : bool = my_set contains 3
const set_size : nat = size (my_set)
const larger_set : int_set = set_add (4, my_set)
const smaller_set : int_set = set_remove (3, my_set)
function update (var s : set (int)) : set (int) is block {
patch s with set [4; 7]
} with s
const new_set : set (int) = update (my_set)
function sum (const acc : int; const i : int): int is acc + i
const sum_of_elements : int = set_fold (sum, my_set, 0)
function loop (const s : set (int)) : int is block {
var sum : int := 0;
for element in set s block {
sum := sum + element
}
} with sum

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@ -0,0 +1,16 @@
type int_set = int set
let my_set : int_set =
Set.add 3 (Set.add 2 (Set.add 2 (Set.add 1 (Set.empty : int set))))
let contains_3 : bool = Set.mem 3 my_set
let set_size : nat = Set.size my_set
let larger_set : int_set = Set.add 4 my_set
let smaller_set : int_set = Set.remove 3 my_set
let sum (acc, i : int * int) : int = acc + i
let sum_of_elements : int = Set.fold sum my_set 0

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@ -0,0 +1,16 @@
type int_set = set (int);
let my_set : int_set =
Set.add (3, Set.add (2, Set.add (2, Set.add (1, Set.empty : set (int)))));
let contains_3 : bool = Set.mem (3, my_set);
let set_size : nat = Set.size (my_set);
let larger_set : int_set = Set.add (4, my_set);
let smaller_set : int_set = Set.remove (3, my_set);
let sum = ((acc, i) : (int, int)) : int => acc + i;
let sum_of_elements : int = Set.fold (sum, my_set, 0);

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@ -1 +0,0 @@
const a: string = string_concat("Hello ", "World");

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@ -1,2 +0,0 @@
type animalBreed is string;
const dogBreed : animalBreed = "Saluki";

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@ -1,4 +0,0 @@
type int_map is map(int, int);
function get_first(const int_map: int_map): option(int) is int_map[1]
// empty map needs a type annotation
const first: option(int) = get_first(((map end) : int_map ));

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@ -1,19 +0,0 @@
// alias two types
type account is address;
type numberOfTransactions is nat;
// accountData consists of a record with two fields (balance, numberOfTransactions)
type accountData is record
balance: tez;
numberOfTransactions: numberOfTransactions;
end
// our ledger / accountBalances is a map of account <-> accountData
type accountBalances is map(account, accountData);
// pseudo-JSON representation of our map
// { "tz1...": {balance: 10mutez, numberOfTransactions: 5n} }
const ledger: accountBalances = map
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address) -> record
balance = 10mutez;
numberOfTransactions = 5n;
end
end

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@ -1,6 +1,7 @@
// accountBalances is a simple type, a map of address <-> tez
type accountBalances is map(address, tez);
// The type accountBalances denotes maps from addresses to tez
const ledger: accountBalances = map
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address) -> 10mutez
end
type account_balances is map (address, tez)
const ledger : account_balances =
map
[("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address) -> 10mutez]

7
gitlab-pages/docs/language-basics/src/unit-option-pattern-matching/flip.ligo Normal file
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@ -0,0 +1,7 @@
type coin is Head | Tail
function flip (const c : coin) : coin is
case c of
Head -> Tail (Unit) // Unit needed because of a bug
| Tail -> Head (Unit) // Unit needed because of a bug
end

5
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@ -1,7 +1,4 @@
// won't work, use const for global values instead
// var four: int = 4;
function add (const a : int; const b : int) : int is
block {
var c : int := a + b;
var c : int := a + b
} with c

2
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@ -0,0 +1,2 @@
let add (a : int) (b : int) : int =
let c : int = a + b in c

1
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@ -0,0 +1 @@
let age : int = 25

29
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@ -3,14 +3,12 @@ id: strings
title: Strings
---
Strings are defined using the built-in `string` type like this:
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```
const a: string = "Hello Alice";
const a : string = "Hello Alice"
```
<!--CameLIGO-->
```
@ -30,12 +28,9 @@ let a: string = "Hello Alice";
Strings can be concatenated using the `^` operator.
```pascaligo
const name: string = "Alice";
const greeting: string = "Hello";
// Hello Alice
const full_greeting: string = greeting ^ " " ^ name;
// Hello Alice! (alternatively)
const full_greeting_exclamation: string = string_concat(full_greeting, "!");
const name : string = "Alice"
const greeting : string = "Hello"
const full_greeting : string = greeting ^ " " ^ name
```
<!--CameLIGO-->
Strings can be concatenated using the `^` operator.
@ -58,14 +53,13 @@ let full_greeting: string = greeting ++ " " ++ name;
## Slicing strings
Strings can be sliced using the syntax specific built-in built-in function:
Strings can be sliced using a built-in function:
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo
const name: string = "Alice";
// slice = "A"
const slice: string = string_slice(0n, 1n, name);
const name : string = "Alice"
const slice : string = string_slice (0n, 1n, name)
```
<!--CameLIGO-->
```cameligo
@ -79,18 +73,19 @@ let slice: string = String.slice(0n, 1n, name);
```
<!--END_DOCUSAURUS_CODE_TABS-->
> ⚠️ Notice that the `offset` and slice `length` are `nats`
> ⚠️ Notice that the `offset` and slice `length` are natural numbers
> (`nat`).
## Aquiring the length of a string
The length of a string can be found using the syntax specific built-in function:
The length of a string can be found using a built-in function:
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo
const name: string = "Alice";
const name : string = "Alice"
// length = 5
const length: nat = size(name);
const length : nat = size (name)
```
<!--CameLIGO-->
```cameligo

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@ -3,38 +3,45 @@ id: tezos-specific
title: Tezos Domain-Specific Operations
---
LIGO is a language for writing Tezos smart contracts. It would be a little odd if
it didn't have any Tezos specific functions. This page will tell you about them.
LIGO is a programming language for writing Tezos smart contracts. It
would be a little odd if it did not have any Tezos specific
functions. This page will tell you about them.
## Pack and Unpack
## Pack and unpack
Michelson provides the `PACK` and `UNPACK` instructions for data serialization.
`PACK` converts Michelson data structures to a binary format, and `UNPACK`
reverses it. This functionality can be accessed from within LIGO.
Michelson provides the `PACK` and `UNPACK` instructions for data
serialization. The instruction `PACK` converts Michelson data
structures into a binary format, and `UNPACK` reverses that
transformation. This functionality can be accessed from within LIGO.
> ⚠️ `PACK` and `UNPACK` are features of Michelson that are intended to be used by people that really know what they're doing. There are several failure cases (such as `UNPACK`ing a lambda from an untrusted source), most of which are beyond the scope of this document. Don't use these functions without doing your homework first.
> ⚠️ `PACK` and `UNPACK` are Michelson instructions that are intended
> to be used by people that really know what they are doing. There are
> several risks and failure cases, such as unpacking a lambda from an
> untrusted source, and most of which are beyond the scope of this
> document. Do not use these functions without doing your homework
> first.
<!--DOCUSAURUS_CODE_TABS-->
<!--PascaLIGO-->
```pascaligo
```pascaligo group=a
function id_string (const p : string) : option (string) is block {
const packed : bytes = bytes_pack(p) ;
const packed : bytes = bytes_pack (p)
} with (bytes_unpack (packed): option (string))
```
<!--CameLIGO-->
```cameligo
```cameligo group=a
let id_string (p : string) : string option =
let packed: bytes = Bytes.pack p in
((Bytes.unpack packed): string option)
(Bytes.unpack packed : string option)
```
<!--ReasonLIGO-->
```reasonligo
```reasonligo group=a
let id_string = (p : string) : option (string) => {
let packed : bytes = Bytes.pack (p);
((Bytes.unpack(packed)): option(string));
(Bytes.unpack(packed) : option (string));
};
```
@ -42,41 +49,35 @@ let id_string = (p: string) : option(string) => {
## Hashing Keys
It's often desirable to hash a public key. In Michelson, certain data structures
such as maps will not allow the use of the `key` type. Even if this weren't the case
hashes are much smaller than keys, and storage on blockchains comes at a cost premium.
You can hash keys with the `key_hash` type and associated built in function.
It is often desirable to hash a public key. In Michelson, certain data
structures such as maps will not allow the use of the `key` type. Even
if this were not the case, hashes are much smaller than keys, and
storage on blockchains comes at a cost premium. You can hash keys an
predefined function returning a value of type `key_hash`.
<!--DOCUSAURUS_CODE_TABS-->
<!--PascaLIGO-->
```pascaligo
```pascaligo group=b
function check_hash_key (const kh1 : key_hash; const k2 : key) : bool * key_hash is block {
var ret : bool := False;
var kh2 : key_hash := crypto_hash_key (k2);
if kh1 = kh2 then ret := True else skip;
if kh1 = kh2 then ret := True else skip
} with (ret, kh2)
```
<!--CameLIGO-->
```cameligo
```cameligo group=b
let check_hash_key (kh1, k2 : key_hash * key) : bool * key_hash =
let kh2 : key_hash = Crypto.hash_key k2 in
if kh1 = kh2
then (true, kh2)
else (false, kh2)
if kh1 = kh2 then true, kh2 else false, kh2
```
<!--ReasonLIGO-->
```reasonligo
```reasonligo group=b
let check_hash_key = ((kh1, k2) : (key_hash, key)) : (bool, key_hash) => {
let kh2 : key_hash = Crypto.hash_key(k2);
if (kh1 == kh2) {
(true, kh2);
}
else {
(false, kh2);
}
if (kh1 == kh2) { (true, kh2); } else { (false, kh2); }
};
```
@ -84,17 +85,20 @@ let check_hash_key = ((kh1, k2): (key_hash, key)) : (bool, key_hash) => {
## Checking Signatures
Sometimes a contract will want to check that a message has been signed by a
particular key. For example, a point-of-sale system might want a customer to
sign a transaction so it can be processed asynchronously. You can do this in LIGO
using the `key` and `signature` types.
Sometimes a contract will want to check that a message has been signed
by a particular key. For example, a point-of-sale system might want a
customer to sign a transaction so it can be processed
asynchronously. You can do this in LIGO using the `key` and
`signature` types.
> ⚠️ There is no way to *generate* a signed message in LIGO. This is because that would require storing a private key on chain, at which point it isn't very private anymore.
> ⚠️ There is no way to *generate* a signed message in LIGO. This is
> because that would require storing a private key on chain, at which
> point it is not... private anymore.
<!--DOCUSAURUS_CODE_TABS-->
<!--PascaLIGO-->
```pascaligo
```pascaligo group=c
function check_signature
(const pk : key;
const signed : signature;
@ -103,41 +107,44 @@ function check_signature
```
<!--CameLIGO-->
```cameligo
```cameligo group=c
let check_signature (pk, signed, msg : key * signature * bytes) : bool =
Crypto.check pk signed msg
```
<!--ReasonLIGO-->
```reasonligo
let check_signature = ((pk, signed, msg): (key, signature, bytes)) : bool => {
```reasonligo group=c
let check_signature =
((pk, signed, msg) : (key, signature, bytes)) : bool => {
Crypto.check (pk, signed, msg);
};
```
<!--END_DOCUSAURUS_CODE_TABS-->
## Getting The Contract's Own Address
## Getting the contract's own address
Often you want to get the address of the contract being executed. You can do it with
`self_address`.
Often you want to get the address of the contract being executed. You
can do it with `self_address`.
> ⚠️ Due to limitations in Michelson, self_address in a contract is only allowed at the entry-point level. Using it in a utility function will cause an error.
> ⚠️ Due to limitations in Michelson, `self_address` in a contract is
> only allowed at the entry-point level (a.k.a top-level). Using it in
> an auxiliaru function will cause an error.
<!--DOCUSAURUS_CODE_TABS-->
<!--PascaLIGO-->
```pascaligo
const current_addr : address = self_address;
```pascaligo group=d
const current_addr : address = self_address
```
<!--CameLIGO-->
```cameligo
```cameligo group=d
let current_addr : address = Current.self_address
```
<!--ReasonLIGO-->
```reasonligo
```reasonligo group=d
let current_addr : address = Current.self_address;
```

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@ -3,163 +3,189 @@ id: types
title: Types
---
LIGO is strongly and statically typed. This means that the compiler checks your program at compilation time and makes sure there won't be any type related runtime errors. LIGO types are built on top of Michelson's type system.
LIGO is strongly and statically typed. This means that the compiler
checks your program at compilation time and, if it passes the tests,
this ensures that there will be no runtime error due to wrong
assumptions on the data. This is called *type checking*.
LIGO types are built on top of Michelson's type system.
## Built-in types
For quick referrence, you can find all the built-in types [here](https://gitlab.com/ligolang/ligo/blob/dev/src/passes/operators/operators.ml#L35).
For quick reference, you can find all the built-in types [here](https://gitlab.com/ligolang/ligo/blob/dev/src/passes/operators/operators.ml#L35).
## Type aliases
Type aliasing is great for creating a readable / maintainable smart contract. One well typed type/variable is worth a thousand words. For example we can choose to *alias* a string as an animal breed - this will allow us to comunicate our intent with added clarity.
*Type aliasing* consists in renaming a given type, when the context
calls for a more precise name. This increases readability and
maintainability of your smart contracts. For example we can choose to
alias a string type as an animal breed - this will allow us to
comunicate our intent with added clarity.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo
type animalBreed is string;
const dogBreed : animalBreed = "Saluki";
```pascaligo group=a
type breed is string
const dog_breed : breed = "Saluki"
```
<!--CameLIGO-->
```cameligo
type animal_breed = string
let dog_breed: animal_breed = "Saluki"
```cameligo group=a
type breed = string
let dog_breed : breed = "Saluki"
```
<!--ReasonLIGO-->
```reasonligo
type animal_breed = string;
let dog_breed: animal_breed = "Saluki";
```reasonligo group=a
type breed = string;
let dog_breed : breed = "Saluki";
```
<!--END_DOCUSAURUS_CODE_TABS-->
> Types in LIGO are `structural`, which means that `animalBreed`/`animal_breed` and `string` are interchangable and are considered equal.
> The above type definitions are aliases, which means that `breed` and
> `string` are interchangable in all contexts.
## Simple types
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo
// accountBalances is a simple type, a map of address <-> tez
type accountBalances is map(address, tez);
```pascaligo group=b
// The type accountBalances denotes maps from addresses to tez
type account_balances is map (address, tez)
const ledger : account_balances =
map
[("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address) -> 10mutez]
const ledger: accountBalances = map
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address) -> 10mutez
end
```
<!--CameLIGO-->
```cameligo
// account_balances is a simple type, a map of address <-> tez
```cameligo group=b
// The type account_balances denotes maps from addresses to tez
type account_balances = (address, tez) map
let ledger: account_balances = Map.literal
let ledger : account_balances =
Map.literal
[(("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address), 10mutez)]
```
<!--ReasonLIGO-->
```reasonligo
(* account_balances is a simple type, a map of address <-> tez *)
```reasonligo group=b
// The type account_balances denotes maps from addresses to tez
type account_balances = map (address, tez);
let ledger: account_balances =
Map.literal([
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address, 10mutez)
]);
Map.literal
([("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address, 10mutez)]);
```
<!--END_DOCUSAURUS_CODE_TABS-->
## Composed types
## Structured types
Often contracts require complex data structures, which in turn require well-typed storage or functions to work with. LIGO offers a simple way to compose simple types into larger & more expressive composed types.
Often contracts require complex data structures, which in turn require
well-typed storage or functions to work with. LIGO offers a simple way
to compose simple types into *structured types*.
In the example below you can see the definition of data types for a ledger that keeps the balance and number of previous transactions for a given account.
The first of those structured types is the *record*, which aggregates
types as *fields* and index them with a *field name*. In the example
below you can see the definition of data types for a ledger that keeps
the balance and number of previous transactions for a given account.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo
// alias two types
type account is address;
type numberOfTransactions is nat;
// accountData consists of a record with two fields (balance, numberOfTransactions)
type accountData is record
balance: tez;
numberOfTransactions: numberOfTransactions;
end
// our ledger / accountBalances is a map of account <-> accountData
type accountBalances is map(account, accountData);
```pascaligo group=c
// Type aliasing
type account is address
type number_of_transactions is nat
// pseudo-JSON representation of our map
// { "tz1...": {balance: 10mutez, numberOfTransactions: 5n} }
const ledger: accountBalances = map
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address) -> record
// The type account_data is a record with two fields.
type account_data is record [
balance : tez;
transactions : number_of_transactions
]
// A ledger is a map from accounts to account_data
type ledger is map (account, account_data)
const my_ledger : ledger = map [
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address) ->
record [
balance = 10mutez;
numberOfTransactions = 5n;
end
end
transactions = 5n
]
]
```
<!--CameLIGO-->
```cameligo
(* alias two types *)
```cameligo group=c
// Type aliasing
type account = address
type number_of_transactions = nat
(* account_data consists of a record with two fields (balance, number_of_transactions) *)
// The type account_data is a record with two fields.
type account_data = {
balance : tez;
number_of_transactions: number_of_transactions;
transactions : number_of_transactions
}
(* our ledger / account_balances is a map of account <-> account_data *)
type account_balances = (account, account_data) map
// A ledger is a map from accounts to account_data
type ledger = (account, account_data) map
// pseudo-JSON representation of our map
// {"tz1...": {balance: 10mutez, number_of_transactions: 5n}}
let ledger: account_balances = Map.literal
let my_ledger : ledger = Map.literal
[(("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address),
{balance = 10mutez;
number_of_transactions = 5n;}
)]
{balance = 10mutez; transactions = 5n})]
```
<!--ReasonLIGO-->
```reasonligo
(* alias two types *)
```reasonligo group=c
// Type aliasing
type account = address;
type number_of_transactions = nat;
(* account_data consists of a record with two fields (balance, number_of_transactions) *)
// The type account_data is a record with two fields.
type account_data = {
balance : tez,
number_of_transactions,
transactions : number_of_transactions
};
(* our ledger / account_balances is a map of account <-> account_data *)
type account_balances = map(account, account_data);
(* pseudo-JSON representation of our map
{"tz1...": {balance: 10mutez, number_of_transactions: 5n}} *)
let ledger: account_balances =
// A ledger is a map from accounts to account_data
type ledger = map (account, account_data);
let my_ledger : ledger =
Map.literal([
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address,
{balance: 10mutez, number_of_transactions: 5n})
]);
{balance: 10mutez, transactions: 5n})]);
```
The structured types which are dual to records are the *variant types*
and they are described in the section about *pattern matching*. They
are dual because records are a product of types (types are bundled
into a record), whereas variant types are a sum of types (they are
exclusive to each other).
<!--END_DOCUSAURUS_CODE_TABS-->
## Annotations
In certain cases, type of an expression cannot be properly determined. This can be circumvented by annotating an expression with it's desired type, here's an example:
In certain cases, the type of an expression cannot be properly
inferred by the compiler. In order to help the type checke, you can
annotate an expression with its desired type. Here is an example:
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo
type int_map is map(int, int);
function get_first(const int_map: int_map): option(int) is int_map[1]
// empty map needs a type annotation
const first: option(int) = get_first(((map end) : int_map ));
type int_map is map (int, int)
function get_first (const my_map : int_map): option (int) is my_map[1]
// The empty map always needs a type annotation
const first : option (int) = get_first (((map end) : int_map))
```
<!--END_DOCUSAURUS_CODE_TABS-->

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@ -3,110 +3,162 @@ id: unit-option-pattern-matching
title: Unit, Option, Pattern matching
---
Optionals are a programing pattern seen in OCaml. Since Michelson and LIGO are both inspired by OCaml, you'll have the *option* to use them in LIGO as well.
Optionals are a pervasive programing pattern in OCaml. Since Michelson
and LIGO are both inspired by OCaml, *optional types* are available in
LIGO as well. Similarly, OCaml features a *unit* type, and LIGO
features it as well. Both the option type and the unit types are
instances of a more general kind of types: *variant types* (sometimes
called *sum types*).
## Type unit
## The unit type
Units in Michelson or LIGO represent *for the lack of better words* - an empty/useless/not needed value.
The `unit` type in Michelson or LIGO is a predefined type that
contains only one value that carries no information. It is used when
no relevant information is required or produced. Here is how it used.
Here's how they're defined:
> 💡 Units come in handy when we try pattern matching on custom variants below.
> 💡 Units come in handy when we try pattern matching on custom
> variants below.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo
const n: unit = Unit;
In PascaLIGO, the unique value of the `unit` type is `Unit`.
```pascaligo group=a
const n : unit = Unit
```
<!--CameLIGO-->
```cameligo
In CameLIGO, the unique value of the `unit` type is `()`, following
the OCaml convention.
```cameligo group=a
let n : unit = ()
```
<!--ReasonLIGO-->
```reasonligo
In ReasonLIGO, the unique value of the `unit` type is `()`, following
the OCaml convention.
```reasonligo group=a
let n : unit = ();
```
<!--END_DOCUSAURUS_CODE_TABS-->
## Variants
## Variant types
Variant is a user-defined or a built-in type (in case of optionals) that can be compared to Enum (from javascript).
A variant type is a user-defined or a built-in type (in case of
options) that defines a type by cases, so a value of a variant type is
either this, or that or... The simplest variant type is equivalent to
the enumerated types found in Java, C++, JavaScript etc.
Here's how to define a new variant type:
Here is how we define a coin as being either head or tail (and nothing
else):
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo
type id is nat
type user is
| Admin of id
| Manager of id
| Guest;
const u: user = Admin(1000n);
const g: user = Guest(Unit);
```pascaligo group=b
type coin is Head | Tail
const head : coin = Head (Unit) // Unit needed because of a bug
const tail : coin = Tail (Unit) // Unit needed because of a bug
```
<!--CameLIGO-->
```cameligo
type id = nat
type user =
| Admin of id
| Manager of id
| Guest of unit
let u: user = Admin 1000n
let g: user = Guest ()
```cameligo group=b
type coin = Head | Tail
let head : coin = Head
let tail : coin = Tail
```
<!--ReasonLIGO-->
```reasonligo
```reasonligo group=b
type coin = | Head | Tail;
let head : coin = Head;
let tail : coin = Tail;
```
<!--END_DOCUSAURUS_CODE_TABS-->
The names `Head` and `Tail` in the definition of the type `coin` are
called *data constructors*, or *variants*.
In general, it is interesting for variants to carry some information,
and thus go beyond enumerated types. In the following, we show how to
define different kinds of users of a system.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo group=c
type id is nat
type user is
Admin of id
| Manager of id
| Guest
const u : user = Admin (1000n)
const g : user = Guest (Unit) // Unit needed because of a bug
```
<!--CameLIGO-->
```cameligo group=c
type id = nat
type user =
Admin of id
| Manager of id
| Guest
let u : user = Admin 1000n
let g : user = Guest
```
<!--ReasonLIGO-->
```reasonligo group=c
type id = nat;
type user =
| Admin (id)
| Manager (id)
| Guest(unit);
| Guest;
let u : user = Admin (1000n);
let g: user = Guest();
let g : user = Guest;
```
<!--END_DOCUSAURUS_CODE_TABS-->
Defining a varient can be extremely useful for building semantically appealing contracts. We'll learn how to use variants for 'logic purposes' shortly.
Defining a variant can be extremely useful for building semantically
appealing contracts. We will learn how to use variants for "logic
purposes"' shortly.
## Optional values
Optionals are a type of built-in variant that can be used to determine if a variable holds a certain value or not. This is especially useful when (for example) your program's state allows for a certain variable value to be empty, like this:
The `option` type is a predefined variant type that is used to express
whether there is a value of some type or none. This is especially
useful when calling a *partial function*, that is, a function that is
not defined for some inputs. In that case, the value of the `option`
type would be `None`, otherwise `Some (v)`, where `v` is some
meaningful value *of any type*. An example in arithmetic is the
division operation:
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo
type dinner is option(string);
// stay hungry
const p1: dinner = None;
// have some hamburgers
const p2: dinner = Some("Hamburgers")
```pascaligo group=d
function div (const a : nat; const b : nat) : option (nat) is
if b = 0n then (None: option (nat)) else Some (a/b)
```
<!--CameLIGO-->
```cameligo
type dinner = string option
let p1: dinner = None
let p2: dinner = Some "Hamburgers"
```cameligo group=d
let div (a, b : nat * nat) : nat option =
if b = 0n then (None: nat option) else Some (a/b)
```
<!--ReasonLIGO-->
```reasonligo
type dinner = option(string);
let p1: dinner = None;
let p2: dinner = Some("Hamburgers");
```reasonligo group=d
let div = ((a, b) : (nat, nat)) : option (nat) =>
if (b == 0n) { (None: option (nat)); } else { Some (a/b); };
```
<!--END_DOCUSAURUS_CODE_TABS-->
@ -114,38 +166,66 @@ let p2: dinner = Some("Hamburgers");
## Pattern matching
Pattern matching is very similiar to e.g. `switch` in Javascript, and can be used to re-route the program's flow based on a value of a variant.
*Pattern matching* is similiar to the `switch` construct in
Javascript, and can be used to route the program's control flow based
on the value of a variant. Consider for example the definition of a
function `flip` that flips a coin, as defined above.
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo
type dinner is option(string);
function is_hungry(const dinner: dinner): bool is block { skip }
with (
case dinner of
| None -> True
| Some(d) -> False
```pascaligo group=e
type coin is Head | Tail
function flip (const c : coin) : coin is
case c of
Head -> Tail (Unit) // Unit needed because of a bug
| Tail -> Head (Unit) // Unit needed because of a bug
end
)
```
You can call the function `flip` by using the LIGO compiler like so:
```shell
ligo run-function
gitlab-pages/docs/language-basics/src/unit-option-pattern-matching/flip.ligo
flip "(Head (Unit))"
# Outputs: Tail(Unit)
```
<!--CameLIGO-->
```cameligo
type dinner = string option
let is_hungry (d: dinner) : bool =
match d with
| None -> true
| Some s -> false
```cameligo group=e
type coin = Head | Tail
let flip (c : coin) : coin =
match c with
Head -> Tail
| Tail -> Head
```
You can call the function `flip` by using the LIGO compiler like so:
```shell
ligo run-function
gitlab-pages/docs/language-basics/src/unit-option-pattern-matching/flip.mligo
flip Head
# Outputs: Tail(Unit)
```
<!--ReasonLIGO-->
```reasonligo
type dinner = option(string);
let is_hungry = (d: dinner): bool =>
switch (d) {
| None => true
| Some(s) => false
```reasonligo group=e
type coin = | Head | Tail;
let flip = (c : coin) : coin =>
switch (c) {
| Head => Tail
| Tail => Head
};
```
You can call the function `flip` by using the LIGO compiler like so:
```shell
ligo run-function
gitlab-pages/docs/language-basics/src/unit-option-pattern-matching/flip.religo
flip Head
# Outputs: Tail(Unit)
```
<!--END_DOCUSAURUS_CODE_TABS-->

95
gitlab-pages/docs/language-basics/variables-and-constants.md
View File

@ -3,43 +3,48 @@ id: constants-and-variables
title: Constants & Variables
---
The next building block after types are constants and variables.
The next building block after types are *constants* and *variables*.
## Constants
Constants are immutable by design, which means their values can't be reassigned.
When defining a constant you need to provide a `name`, `type` and a `value`:
Constants are immutable by design, which means their values cannot be
reassigned. Put in another way, they can be assigned once, at their
declaration. When defining a constant you need to provide a `name`,
`type` and a `value`:
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
```pascaligo
const age : int = 25;
```pascaligo group=a
const age : int = 25
```
You can evaluate the constant definition above using the following CLI command:
You can evaluate the constant definition above using the following CLI
command:
```shell
ligo evaluate-value -s pascaligo gitlab-pages/docs/language-basics/src/variables-and-constants/const.ligo age
ligo evaluate-value gitlab-pages/docs/language-basics/src/variables-and-constants/const.ligo age
# Outputs: 25
```
<!--CameLIGO-->
```cameligo
```cameligo group=a
let age : int = 25
```
You can evaluate the constant definition above using the following CLI command:
You can evaluate the constant definition above using the following CLI
command:
```shell
ligo evaluate-value -s cameligo gitlab-pages/docs/language-basics/src/variables-and-constants/const.mligo age
ligo evaluate-value gitlab-pages/docs/language-basics/src/variables-and-constants/const.mligo age
# Outputs: 25
```
<!--ReasonLIGO-->
```reasonligo
```reasonligo group=a
let age : int = 25;
```
You can evaluate the constant definition above using the following CLI command:
You can evaluate the constant definition above using the following CLI
command:
```shell
ligo evaluate-value -s reasonligo gitlab-pages/docs/language-basics/src/variables-and-constants/const.religo age
ligo evaluate-value gitlab-pages/docs/language-basics/src/variables-and-constants/const.religo age
# Outputs: 25
```
@ -50,74 +55,78 @@ ligo evaluate-value -s reasonligo gitlab-pages/docs/language-basics/src/variable
<!--DOCUSAURUS_CODE_TABS-->
<!--Pascaligo-->
Variables, unlike constants, are mutable. They can't be used in a *global scope*, but they can be used within functions, or function arguments.
Variables, unlike constants, are mutable. They cannot be declared in a
*global scope*, but they can be declared and used within functions, or
as function parameters.
> 💡 Don't worry if you don't understand the function syntax yet. We'll get to it in upcoming sections of the docs.
> 💡 Do not worry if you do not understand the function syntax yet. We
> will get to it in upcoming sections of this documentation.
> ⚠️ Please be wary that mutation only works within the function scope itself, values outside of the function scope will not be affected.
> ⚠️ Please be wary that mutation only works within the function scope
> itself, values outside of the function scope will not be affected.
```pascaligo
// won't work, use const for global values instead
// var four: int = 4;
```pascaligo group=b
// The following is invalid: use `const` for global values instead.
// var four : int = 4
function add (const a : int; const b : int) : int is
block {
var c : int := a + b;
var c : int := a + b
} with c
```
> ⚠️ Notice the assignment operator `:=` for `var`, instead of `=` for
> constants.
> ⚠️ Notice the different assignment operator `:=`
You can run the `add` function defined above using the LIGO compiler like this:
You can run the `add` function defined above using the LIGO compiler
like this:
```shell
ligo run-function -s pascaligo gitlab-pages/docs/language-basics/src/variables-and-constants/add.ligo add '(1,1)'
ligo run-function gitlab-pages/docs/language-basics/src/variables-and-constants/add.ligo add '(1,1)'
# Outputs: 2
```
<!--CameLIGO-->
As expected from a functional language, CameLIGO uses value-binding
for variables rather than assignment. Variables are changed by replacement,
with a new value being bound in place of the old one.
As expected in the pure subset of a functional language, CameLIGO only
features constant values: once they are declared, the value cannot be
changed (or "mutated").
> 💡 Don't worry if you don't understand the function syntax yet. We'll get to it in upcoming sections of the docs.
```cameligo
> 💡 Do not worry if you do not understand the function syntax yet. We
> will get to it in upcoming sections of this documentation.
```cameligo group=c
let add (a : int) (b : int) : int =
let c : int = a + b in c
```
You can run the `add` function defined above using the LIGO compiler like this:
You can run the `add` function defined above using the LIGO compiler
like this:
```shell
ligo run-function -s cameligo gitlab-pages/docs/language-basics/src/variables-and-constants/add.mligo add '(1,1)'
ligo run-function gitlab-pages/docs/language-basics/src/variables-and-constants/add.mligo add '(1,1)'
# Outputs: 2
```
<!--ReasonLIGO-->
As expected from a functional language, ReasonLIGO uses value-binding
for variables rather than assignment. Variables are changed by replacement,
with a new value being bound in place of the old one.
As expected in the pure subset of a functional language, ReasonLIGO
only features constant values: once they are declared, the value
cannot be changed (or "mutated").
> 💡 Don't worry if you don't understand the function syntax yet. We'll get to it in upcoming sections of the docs.
```reasonligo
> 💡 Do not worry if you do not understand the function syntax yet. We
> will get to it in upcoming sections of this documentation.
```reasonligo group=c
let add = ((a, b): (int, int)): int => {
let c : int = a + b;
c;
};
```
You can run the `add` function defined above using the LIGO compiler like this:
You can run the `add` function defined above using the LIGO compiler
like this:
```shell
ligo run-function -s reasonligo gitlab-pages/docs/language-basics/src/variables-and-constants/add.religo add '(1,1)'
ligo run-function gitlab-pages/docs/language-basics/src/variables-and-constants/add.religo add '(1,1)'
# Outputs: 2
```

6
src/bin/expect_tests/lexer_tests.ml
View File

@ -106,7 +106,7 @@ ligo: : Lexical error in file "negative_byte_sequence.religo", line 1, character
run_ligo_bad [ "compile-contract" ; "../../test/lexer/reserved_name.ligo" ; "main" ] ;
[%expect {|
ligo: : Lexical error in file "reserved_name.ligo", line 1, characters 4-13:
Reserved name: arguments.
Reserved name: "arguments".
Hint: Change the name.
{}
@ -123,7 +123,7 @@ ligo: : Lexical error in file "reserved_name.ligo", line 1, characters 4-13:
run_ligo_bad [ "compile-contract" ; "../../test/lexer/reserved_name.religo" ; "main" ] ;
[%expect {|
ligo: : Lexical error in file "reserved_name.religo", line 1, characters 4-7:
Reserved name: end.
Reserved name: "end".
Hint: Change the name.
{}
@ -140,7 +140,7 @@ ligo: : Lexical error in file "reserved_name.religo", line 1, characters 4-7:
run_ligo_bad [ "compile-contract" ; "../../test/lexer/reserved_name.mligo" ; "main" ] ;
[%expect {|
ligo: : Lexical error in file "reserved_name.mligo", line 1, characters 4-10:
Reserved name: object.
Reserved name: "object".
Hint: Change the name.
{}