511 lines
12 KiB
Markdown
511 lines
12 KiB
Markdown
---
|
|
id: maps-records
|
|
title: Maps, Records
|
|
---
|
|
|
|
So far we've seen pretty basic data types. LIGO also offers more complex built-in constructs, such as Maps and Records.
|
|
|
|
## Maps
|
|
|
|
Maps are natively available in Michelson, and LIGO builds on top of them. A requirement for a Map is that its keys be of the same type, and that type must be comparable.
|
|
|
|
Here's how a custom map type is defined:
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
type move is (int * int);
|
|
type moveset is map(address, move);
|
|
```
|
|
|
|
<!--CameLIGO-->
|
|
```cameligo
|
|
type move = int * int
|
|
type moveset = (address, move) map
|
|
```
|
|
|
|
<!--ReasonLIGO-->
|
|
```reasonligo
|
|
type move = (int, int);
|
|
type moveset = map(address, move);
|
|
```
|
|
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
And here's how a map value is populated:
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
|
|
```pascaligo
|
|
const moves: moveset = map
|
|
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address) -> (1, 2);
|
|
("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address) -> (0, 3);
|
|
end
|
|
```
|
|
> Notice the `->` between the key and its value and `;` to separate individual map entries.
|
|
>
|
|
> `("<string value>": address)` means that we type-cast a string into an address.
|
|
|
|
<!--CameLIGO-->
|
|
|
|
```cameligo
|
|
let moves: moveset = Map.literal
|
|
[ (("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address), (1, 2)) ;
|
|
(("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address), (0, 3)) ;
|
|
]
|
|
```
|
|
> Map.literal constructs the map from a list of key-value pair tuples, `(<key>, <value>)`.
|
|
> Note also the `;` to separate individual map entries.
|
|
>
|
|
> `("<string value>": address)` means that we type-cast a string into an address.
|
|
|
|
<!--ReasonLIGO-->
|
|
|
|
```reasonligo
|
|
let moves : moveset =
|
|
Map.literal([
|
|
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address, (1, 2)),
|
|
("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address, (0, 3)),
|
|
]);
|
|
```
|
|
> Map.literal constructs the map from a list of key-value pair tuples, `(<key>, <value>)`.
|
|
>
|
|
> `("<string value>": address)` means that we type-cast a string into an address.
|
|
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
### Accessing map values by key
|
|
|
|
If we want to access a move from our moveset above, we can use the `[]` operator/accessor to read the associated `move` value. However, the value we'll get will be wrapped as an optional; in our case `option(move)`. Here's an example:
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
const my_balance : option(move) = moves[("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address)];
|
|
```
|
|
|
|
<!--CameLIGO-->
|
|
|
|
```cameligo
|
|
let my_balance : move option = Map.find_opt ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address) moves
|
|
```
|
|
|
|
<!--ReasonLIGO-->
|
|
|
|
```reasonligo
|
|
let my_balance : option(move) =
|
|
Map.find_opt("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address, moves);
|
|
```
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
#### Obtaining a map value forcefully
|
|
|
|
Accessing a value in a map yields an option, however you can also get the value directly:
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
const my_balance : move = get_force(("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address), moves);
|
|
```
|
|
|
|
<!--CameLIGO-->
|
|
|
|
```cameligo
|
|
let my_balance : move = Map.find ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address) moves
|
|
```
|
|
|
|
<!--ReasonLIGO-->
|
|
|
|
```reasonligo
|
|
let my_balance : move =
|
|
Map.find("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address, moves);
|
|
```
|
|
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
### Updating the contents of a map
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
|
|
<!--Pascaligo-->
|
|
|
|
The values of a PascaLIGO map can be updated using the ordinary assignment syntax:
|
|
|
|
```pascaligo
|
|
|
|
function set_ (var m: moveset) : moveset is
|
|
block {
|
|
m[("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address)] := (4,9);
|
|
} with m
|
|
```
|
|
|
|
<!--Cameligo-->
|
|
|
|
We can update a map in CameLIGO using the `Map.update` built-in:
|
|
|
|
```cameligo
|
|
|
|
let updated_map: moveset = Map.update ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address) (Some (4,9)) moves
|
|
```
|
|
|
|
<!--Reasonligo-->
|
|
|
|
We can update a map in ReasonLIGO using the `Map.update` built-in:
|
|
|
|
```reasonligo
|
|
|
|
let updated_map: moveset = Map.update(("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address), Some((4,9)), moves);
|
|
```
|
|
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
|
|
### Iteration over the contents of a map
|
|
|
|
There are three kinds of iteration on LIGO maps, `iter`, `map` and `fold`. `iter`
|
|
is an iteration over the map with no return value, its only use is to
|
|
generate side effects. This can be useful if for example you would like to check
|
|
that each value inside of a map is within a certain range, with an error thrown
|
|
otherwise.
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
function iter_op (const m : moveset) : unit is
|
|
block {
|
|
function aggregate (const i : address ; const j : move) : unit is block
|
|
{ if (j.1 > 1) then skip else failwith("fail") } with unit ;
|
|
} with map_iter(aggregate, m) ;
|
|
```
|
|
|
|
<!--CameLIGO-->
|
|
```cameligo
|
|
let iter_op (m : moveset) : unit =
|
|
let assert_eq = fun (i: address * move) -> assert (i.1.0 > 1)
|
|
in Map.iter assert_eq m
|
|
```
|
|
|
|
<!--ReasonLIGO-->
|
|
```reasonligo
|
|
let iter_op = (m: moveset): unit => {
|
|
let assert_eq = (i: (address, move)) => assert(i[1][0] > 1);
|
|
Map.iter(assert_eq, m);
|
|
};
|
|
```
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
`map` is a way to create a new map by modifying the contents of an existing one.
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
function map_op (const m : moveset) : moveset is
|
|
block {
|
|
function increment (const i : address ; const j : move) : move is block { skip } with (j.0, j.1 + 1) ;
|
|
} with map_map(increment, m) ;
|
|
```
|
|
|
|
<!--CameLIGO-->
|
|
```cameligo
|
|
let map_op (m : moveset) : moveset =
|
|
let increment = fun (i: address * move) -> (i.1.0, i.1.1 + 1)
|
|
in Map.map increment m
|
|
```
|
|
|
|
<!--ReasonLIGO-->
|
|
```reasonligo
|
|
let map_op = (m: moveset): moveset => {
|
|
let increment = (i: (address, move)) => (i[1][0], i[1][1] + 1);
|
|
Map.map(increment, m);
|
|
};
|
|
```
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
`fold` is an aggregation function that return the combination of a maps contents.
|
|
|
|
The fold is a loop which extracts an element of the map on each iteration. It then
|
|
provides this element and an existing value to a folding function which combines them.
|
|
On the first iteration, the existing value is an initial expression given by the
|
|
programmer. On each subsequent iteration it is the result of the previous iteration.
|
|
It eventually returns the result of combining all the elements.
|
|
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
function fold_op (const m : moveset) : int is
|
|
block {
|
|
function aggregate (const j : int ; const cur : (address * (int * int))) : int is j + cur.1.1 ;
|
|
} with map_fold(aggregate, m , 5)
|
|
```
|
|
|
|
<!--CameLIGO-->
|
|
```cameligo
|
|
let fold_op (m : moveset) : moveset =
|
|
let aggregate = fun (i: int * (address * (int * int))) -> i.0 + i.1.1.1 in
|
|
Map.fold aggregate m 5
|
|
```
|
|
|
|
<!--ReasonLIGO-->
|
|
```reasonligo
|
|
let fold_op = (m: moveset): moveset => {
|
|
let aggregate = (i: (int, (address, (int,int)))) => i[0] + i[1][1][1];
|
|
Map.fold(aggregate, m, 5);
|
|
};
|
|
|
|
```
|
|
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
## Big Maps
|
|
|
|
Ordinary maps are fine for contracts with a finite lifespan or a bounded number
|
|
of users. For many contracts however, the intention is to have a map hold *many*
|
|
entries, potentially millions or billions. The cost of loading these entries into
|
|
the environment each time a user executes the contract would eventually become
|
|
too expensive were it not for big maps. Big maps are a data structure offered by
|
|
Tezos which handles the scaling concerns for us. In LIGO, the interface for big
|
|
maps is analogous to the one used for ordinary maps.
|
|
|
|
Here's how we define a big map:
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
type move is (int * int);
|
|
type moveset is big_map(address, move);
|
|
```
|
|
|
|
<!--CameLIGO-->
|
|
```cameligo
|
|
type move = int * int
|
|
type moveset = (address, move) big_map
|
|
```
|
|
|
|
<!--ReasonLIGO-->
|
|
```reasonligo
|
|
type move = (int, int);
|
|
type moveset = big_map(address, move);
|
|
```
|
|
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
And here's how a map value is populated:
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
|
|
```pascaligo
|
|
const moves: moveset = big_map
|
|
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address) -> (1, 2);
|
|
("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address) -> (0, 3);
|
|
end
|
|
```
|
|
> Notice the `->` between the key and its value and `;` to separate individual map entries.
|
|
>
|
|
> `("<string value>": address)` means that we type-cast a string into an address.
|
|
|
|
<!--CameLIGO-->
|
|
|
|
```cameligo
|
|
let moves: moveset = Big_map.literal
|
|
[ (("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address), (1, 2)) ;
|
|
(("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address), (0, 3)) ;
|
|
]
|
|
```
|
|
> Big_map.literal constructs the map from a list of key-value pair tuples, `(<key>, <value>)`.
|
|
> Note also the `;` to separate individual map entries.
|
|
>
|
|
> `("<string value>": address)` means that we type-cast a string into an address.
|
|
|
|
<!--ReasonLIGO-->
|
|
|
|
```reasonligo
|
|
let moves: moveset =
|
|
Big_map.literal([
|
|
("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx": address, (1, 2)),
|
|
("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address, (0, 3)),
|
|
]);
|
|
```
|
|
> Big_map.literal constructs the map from a list of key-value pair tuples, `(<key>, <value>)`.
|
|
>
|
|
> `("<string value>": address)` means that we type-cast a string into an address.
|
|
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
### Accessing map values by key
|
|
|
|
If we want to access a move from our moveset above, we can use the `[]` operator/accessor to read the associated `move` value. However, the value we'll get will be wrapped as an optional; in our case `option(move)`. Here's an example:
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
const my_balance : option(move) = moves[("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address)];
|
|
```
|
|
|
|
<!--CameLIGO-->
|
|
|
|
```cameligo
|
|
let my_balance : move option = Big_map.find_opt ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address) moves
|
|
```
|
|
|
|
<!--ReasonLIGO-->
|
|
|
|
```reasonligo
|
|
let my_balance : option(move) =
|
|
Big_map.find_opt("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address, moves);
|
|
```
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
#### Obtaining a map value forcefully
|
|
|
|
Accessing a value in a map yields an option, however you can also get the value directly:
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
const my_balance : move = get_force(("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address), moves);
|
|
```
|
|
|
|
<!--CameLIGO-->
|
|
|
|
```cameligo
|
|
let my_balance : move = Big_map.find ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address) moves
|
|
```
|
|
|
|
<!--ReasonLIGO-->
|
|
|
|
```reasonligo
|
|
let my_balance : move = Big_map.find("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address, moves);
|
|
```
|
|
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
### Updating the contents of a big map
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
|
|
<!--Pascaligo-->
|
|
|
|
The values of a PascaLIGO big map can be updated using the ordinary assignment syntax:
|
|
|
|
```pascaligo
|
|
|
|
function set_ (var m : moveset) : moveset is
|
|
block {
|
|
m[("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address)] := (4,9);
|
|
} with m
|
|
```
|
|
|
|
<!--Cameligo-->
|
|
|
|
We can update a big map in CameLIGO using the `Big_map.update` built-in:
|
|
|
|
```cameligo
|
|
|
|
let updated_map : moveset =
|
|
Big_map.update ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address) (Some (4,9)) moves
|
|
```
|
|
|
|
<!--Reasonligo-->
|
|
|
|
We can update a big map in ReasonLIGO using the `Big_map.update` built-in:
|
|
|
|
```reasonligo
|
|
let updated_map: moveset =
|
|
Big_map.update(("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address), Some((4,9)), moves);
|
|
```
|
|
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
## Records
|
|
|
|
Records are a construct introduced in LIGO, and are not natively available in Michelson. The LIGO compiler translates records into Michelson `Pairs`.
|
|
|
|
Here's how a custom record type is defined:
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
type user is record
|
|
id: nat;
|
|
is_admin: bool;
|
|
name: string;
|
|
end
|
|
```
|
|
|
|
<!--CameLIGO-->
|
|
```cameligo
|
|
type user = {
|
|
id: nat;
|
|
is_admin: bool;
|
|
name: string;
|
|
}
|
|
```
|
|
|
|
<!--ReasonLIGO-->
|
|
```reasonligo
|
|
type user = {
|
|
id: nat,
|
|
is_admin: bool,
|
|
name: string
|
|
};
|
|
```
|
|
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
And here's how a record value is populated:
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
const user: user = record
|
|
id = 1n;
|
|
is_admin = True;
|
|
name = "Alice";
|
|
end
|
|
```
|
|
|
|
<!--CameLIGO-->
|
|
```cameligo
|
|
let user: user = {
|
|
id = 1n;
|
|
is_admin = true;
|
|
name = "Alice";
|
|
}
|
|
```
|
|
|
|
<!--ReasonLIGO-->
|
|
```reasonligo
|
|
let user: user = {
|
|
id: 1n,
|
|
is_admin: true,
|
|
name: "Alice"
|
|
};
|
|
```
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|
|
|
|
|
|
### Accessing record keys by name
|
|
|
|
If we want to obtain a value from a record for a given key, we can do the following:
|
|
|
|
<!--DOCUSAURUS_CODE_TABS-->
|
|
<!--Pascaligo-->
|
|
```pascaligo
|
|
const is_admin : bool = user.is_admin;
|
|
```
|
|
|
|
<!--CameLIGO-->
|
|
```cameligo
|
|
let is_admin : bool = user.is_admin
|
|
```
|
|
|
|
<!--ReasonLIGO-->
|
|
```reasonligo
|
|
let is_admin: bool = user.is_admin;
|
|
```
|
|
|
|
<!--END_DOCUSAURUS_CODE_TABS-->
|