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|
@ -119,9 +119,9 @@ use the non-operation `skip`.
|
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|
end
|
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|
end
|
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|
|
end with f
|
|
|
|
end with f
|
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|
|
|
|
|
Like Pascal, PascaLIGO offers procedures, as well as functions. The
|
|
|
|
<!-- Like Pascal, PascaLIGO offers procedures, as well as functions. The -->
|
|
|
|
difference follows the divide between expressions and instructions:
|
|
|
|
<!-- difference follows the divide between expressions and instructions: -->
|
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|
|
function calls are expressions, procedure calls are instructions.
|
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|
|
<!-- function calls are expressions, procedure calls are instructions. -->
|
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|
|
In order for a function to be a candidate to be an entrypoint to the
|
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|
|
In order for a function to be a candidate to be an entrypoint to the
|
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|
|
contract, it needs to return a specific type: `list (operation) *
|
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|
|
contract, it needs to return a specific type: `list (operation) *
|
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|
|
@ -554,7 +554,7 @@ given the declarations (in verbose style)
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|
then the value of `r.f` is `4`.
|
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|
|
then the value of `r.f` is `4`.
|
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|
|
|
|
### Predefined functions, procedures and instructions
|
|
|
|
### Predefined functions instructions
|
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|
|
Beyond a few operators, PascaLIGO features some predefined values and
|
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|
Beyond a few operators, PascaLIGO features some predefined values and
|
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|
|
functions.
|
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|
functions.
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|
@ -590,54 +590,54 @@ string: if `offset + length` is greater than the length of `string`,
|
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|
|
the result is `None`, otherwise `Some (substring)`. See section
|
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|
|
the result is `None`, otherwise `Some (substring)`. See section
|
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|
|
"Options".
|
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|
|
"Options".
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|
#### Lists
|
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|
|
<!-- #### Lists -->
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|
|
PascaLIGO offers two kinds of iterators on lists.
|
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|
<!-- PascaLIGO offers two kinds of iterators on lists. -->
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The first applies a given function to all the items of a given list,
|
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|
<!-- The first applies a given function to all the items of a given list, -->
|
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|
each call returning the predefined value `Unit`. If the function name
|
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|
|
<!-- each call returning the predefined value `Unit`. If the function name -->
|
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|
|
is `f` and the list is `l`, this is expressed as
|
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|
|
<!-- is `f` and the list is `l`, this is expressed as -->
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|
list_iter (l, f);
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|
<!-- list_iter (l, f); -->
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|
|
Note: `list_iter` is a predefined _procedure_. Procedures are
|
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|
|
<!-- Note: `list_iter` is a predefined _procedure_. Procedures are -->
|
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|
|
functions that return `Unit` and whose calls are instructions, not
|
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|
|
<!-- functions that return `Unit` and whose calls are instructions, not -->
|
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|
|
expressions. The same holds for the iterated function `f` here. See
|
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|
|
<!-- expressions. The same holds for the iterated function `f` here. See -->
|
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|
|
section "Declarations/Procedures".
|
|
|
|
<!-- section "Declarations/Procedures". -->
|
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|
|
For an iterator like `list_iter` to be useful, it needs to be able to
|
|
|
|
<!-- For an iterator like `list_iter` to be useful, it needs to be able to -->
|
|
|
|
perform a side effect, which user-defined procedures and functions
|
|
|
|
<!-- perform a side effect, which user-defined procedures and functions -->
|
|
|
|
cannot do. Like so:
|
|
|
|
<!-- cannot do. Like so: -->
|
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|
|
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|
|
function iter (const delta : int; const l : list (int)) : int is
|
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|
|
<!-- function iter (const delta : int; const l : list (int)) : int is -->
|
|
|
|
var acc : int := 0
|
|
|
|
<!-- var acc : int := 0 -->
|
|
|
|
procedure aggregate (const i : int) is
|
|
|
|
<!-- procedure aggregate (const i : int) is -->
|
|
|
|
begin
|
|
|
|
<!-- begin -->
|
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|
|
acc := acc + i
|
|
|
|
<!-- acc := acc + i -->
|
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|
|
end
|
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|
|
<!-- end -->
|
|
|
|
begin
|
|
|
|
<!-- begin -->
|
|
|
|
aggregate (delta); // Has no effect on acc
|
|
|
|
<!-- aggregate (delta); // Has no effect on acc -->
|
|
|
|
list_iter (l, aggregate) // Has an effect on acc
|
|
|
|
<!-- list_iter (l, aggregate) // Has an effect on acc -->
|
|
|
|
end with acc
|
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|
|
<!-- end with acc -->
|
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|
|
|
|
|
|
|
The other predefined iterator on lists is `list_map`. It is useful
|
|
|
|
<!-- The other predefined iterator on lists is `list_map`. It is useful -->
|
|
|
|
when we need to apply a function to all the items of a list and gather
|
|
|
|
<!-- when we need to apply a function to all the items of a list and gather -->
|
|
|
|
them into another list, in the same order as the original items. (In
|
|
|
|
<!-- them into another list, in the same order as the original items. (In -->
|
|
|
|
mathematical terms, `list_map` builds the list of the images through
|
|
|
|
<!-- mathematical terms, `list_map` builds the list of the images through -->
|
|
|
|
the function.) For instance, the function `iter`
|
|
|
|
<!-- the function.) For instance, the function `iter` -->
|
|
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|
|
|
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|
|
|
|
function iter (const l : list (int)) : list (int) is
|
|
|
|
<!-- function iter (const l : list (int)) : list (int) is -->
|
|
|
|
function incr (const i : int) : int is
|
|
|
|
<!-- function incr (const i : int) : int is -->
|
|
|
|
begin
|
|
|
|
<!-- begin -->
|
|
|
|
skip
|
|
|
|
<!-- skip -->
|
|
|
|
end with i+1
|
|
|
|
<!-- end with i+1 -->
|
|
|
|
begin
|
|
|
|
<!-- begin -->
|
|
|
|
skip
|
|
|
|
<!-- skip -->
|
|
|
|
end with list_map (l, incr)
|
|
|
|
<!-- end with list_map (l, incr) -->
|
|
|
|
|
|
|
|
|
|
|
|
will take a list of integers as a parameter and return a list with the
|
|
|
|
<!-- will take a list of integers as a parameter and return a list with the -->
|
|
|
|
integers all incremented, e.g., `iter (list [1;2;3])` evaluates in
|
|
|
|
<!-- integers all incremented, e.g., `iter (list [1;2;3])` evaluates in -->
|
|
|
|
`list [2;3;4]`.
|
|
|
|
<!-- `list [2;3;4]`. -->
|
|
|
|
|
|
|
|
|
|
|
|
#### Sets
|
|
|
|
#### Sets
|
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|
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|
|
|
@ -709,18 +709,13 @@ functions to update sets.
|
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|
|
has value `3`.
|
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|
|
has value `3`.
|
|
|
|
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|
|
|
|
|
|
|
|
|
|
|
- Complete iteration on sets is performed by loops. See section
|
|
|
|
- The iterator `set_iter` is similar to `list_iter`: it takes a set
|
|
|
|
"Loops".
|
|
|
|
and a procedure (or function returning `Unit`) and applies it in
|
|
|
|
|
|
|
|
turn to all the elements of the set.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
- Another form of complete iteration on sets is performed by
|
|
|
|
|
|
|
|
loops. See section "Loops".
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
#### Maps
|
|
|
|
#### Maps
|
|
|
|
|
|
|
|
|
|
|
|
Currently, maps have less support than sets. PascaLIGO offers the
|
|
|
|
Currently, maps have less support than sets. PascaLIGO offers the
|
|
|
|
following functions and procedures on maps:
|
|
|
|
following functions on maps:
|
|
|
|
|
|
|
|
|
|
|
|
- Adding bindings to a map is only possible if the map is mutable,
|
|
|
|
- Adding bindings to a map is only possible if the map is mutable,
|
|
|
|
that is, if it was declared with the annotation `var`, like so, in
|
|
|
|
that is, if it was declared with the annotation `var`, like so, in
|
|
|
|
@ -768,19 +763,8 @@ following functions and procedures on maps:
|
|
|
|
where `sender` is a key and `backers` is a map. If the key is
|
|
|
|
where `sender` is a key and `backers` is a map. If the key is
|
|
|
|
absent in the map, this instruction is a non-operation.
|
|
|
|
absent in the map, this instruction is a non-operation.
|
|
|
|
|
|
|
|
|
|
|
|
- The iterator `map_iter` is similar to `list_iter`: it takes a set
|
|
|
|
- Complete iteration on maps is performed by loops. See section
|
|
|
|
and a procedure (or function returning `Unit`) and applies it in
|
|
|
|
"Loops".
|
|
|
|
turn to all the bindings of the map. The type of the iterated
|
|
|
|
|
|
|
|
procedure/function is expected to be `key * value -> unit`.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
- The iterator `map_map` is similar to `list_map`: it takes a map
|
|
|
|
|
|
|
|
and a function and builds a new map by applying the function to
|
|
|
|
|
|
|
|
all the bindings. In particular, this means that the expected
|
|
|
|
|
|
|
|
return type of the iterated function must be the type of the
|
|
|
|
|
|
|
|
values in the map.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
- Another form of complete iteration on maps is performed by
|
|
|
|
|
|
|
|
loops. See section "Loops".
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
#### Failures
|
|
|
|
#### Failures
|
|
|
|
|
|
|
|
|
|
|
|
@ -800,17 +784,17 @@ can chose.
|
|
|
|
## Declarations
|
|
|
|
## Declarations
|
|
|
|
|
|
|
|
|
|
|
|
There are several kinds of declarations: types, mutable variables,
|
|
|
|
There are several kinds of declarations: types, mutable variables,
|
|
|
|
constants, functions, procedures, fields. Depending on the syntactic
|
|
|
|
constants, functions, fields. Depending on the syntactic context, only
|
|
|
|
context, only some of those declarations will be allowed. Declarations
|
|
|
|
some of those declarations will be allowed. Declarations may be
|
|
|
|
may be separated by a semicolon. (Because each declaration starts with a
|
|
|
|
separated by a semicolon. (Because each declaration starts with a
|
|
|
|
keyword they can be parsed without separators.)
|
|
|
|
keyword they can be parsed without separators.)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
### Types
|
|
|
|
### Types
|
|
|
|
|
|
|
|
|
|
|
|
Type declarations are found only at top-level, that is, outside any
|
|
|
|
Type declarations are found only at top-level, that is, outside any
|
|
|
|
function or procedure. They associate a type name to a type
|
|
|
|
function. They associate a type name to a type expression. The general
|
|
|
|
expression. The general syntax is
|
|
|
|
syntax is
|
|
|
|
|
|
|
|
|
|
|
|
type some_type_name is some_type_expression
|
|
|
|
type some_type_name is some_type_expression
|
|
|
|
|
|
|
|
|
|
|
|
@ -959,27 +943,39 @@ is valid and changes the value of the mutable variable `counter` to be
|
|
|
|
`3n`. This is the semantics found in all imperative languages.
|
|
|
|
`3n`. This is the semantics found in all imperative languages.
|
|
|
|
|
|
|
|
|
|
|
|
IMPORTANT: Mutable variables cannot be declared at top-level, but only
|
|
|
|
IMPORTANT: Mutable variables cannot be declared at top-level, but only
|
|
|
|
in the scope of function and procedure bodies. This is to avoid global
|
|
|
|
in the scope of function bodies. This is to avoid global side effects
|
|
|
|
side effects that hide the control flow and makes static analysis
|
|
|
|
that hide the control flow and makes static analysis extremely
|
|
|
|
extremely difficult.
|
|
|
|
difficult.
|
|
|
|
|
|
|
|
|
|
|
|
### Functions
|
|
|
|
### Functions
|
|
|
|
|
|
|
|
|
|
|
|
Function declarations can occur both at top-level and inside functions
|
|
|
|
Function declarations can occur both at top-level and inside
|
|
|
|
and procedures (in the tradition of Pascal). We saw an example
|
|
|
|
functions, in the tradition of Pascal. For example,
|
|
|
|
earlier:
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
function iter (const l : list (int)) : list (int) is
|
|
|
|
function incr_list (const l : list (int)) : list (int) is
|
|
|
|
function incr (const i : int) : int is
|
|
|
|
function incr_int (const i : int) : int is
|
|
|
|
begin
|
|
|
|
begin
|
|
|
|
skip
|
|
|
|
skip
|
|
|
|
end with i+1
|
|
|
|
end with i+1
|
|
|
|
|
|
|
|
const item : int = 0
|
|
|
|
begin
|
|
|
|
begin
|
|
|
|
skip
|
|
|
|
var temp : list (int) := nil;
|
|
|
|
end with list_map (l, incr)
|
|
|
|
for item in l
|
|
|
|
|
|
|
|
begin
|
|
|
|
|
|
|
|
temp := incr_int (item) # temp
|
|
|
|
|
|
|
|
end;
|
|
|
|
|
|
|
|
var new_l : list (int) := nil;
|
|
|
|
|
|
|
|
for item in temp
|
|
|
|
|
|
|
|
begin
|
|
|
|
|
|
|
|
new_l := item # new_l
|
|
|
|
|
|
|
|
end
|
|
|
|
|
|
|
|
end with new_l
|
|
|
|
|
|
|
|
|
|
|
|
Here, the function `incr` is declared inside the declaration of the
|
|
|
|
Here, the function `incr_int` is declared inside the declaration of
|
|
|
|
function `iter`. The general shape of a function declaration is
|
|
|
|
the function `incr_list`, which take a list of integers and a list
|
|
|
|
|
|
|
|
containing the same integers plus one.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
The general shape of a function declaration is
|
|
|
|
|
|
|
|
|
|
|
|
function my_name ( ... (* parameters here *)) : return_type is
|
|
|
|
function my_name ( ... (* parameters here *)) : return_type is
|
|
|
|
... // local declarations here
|
|
|
|
... // local declarations here
|
|
|
|
@ -1042,7 +1038,7 @@ copies. Let us copy an example seen above:
|
|
|
|
|
|
|
|
|
|
|
|
function iter (const delta : int; const l : list (int)) : int is
|
|
|
|
function iter (const delta : int; const l : list (int)) : int is
|
|
|
|
var acc : int := 0
|
|
|
|
var acc : int := 0
|
|
|
|
procedure aggregate (const i : int) is
|
|
|
|
function aggregate (const i : int) : unit is
|
|
|
|
begin
|
|
|
|
begin
|
|
|
|
acc := acc + i // acc is part of the copied environment
|
|
|
|
acc := acc + i // acc is part of the copied environment
|
|
|
|
end
|
|
|
|
end
|
|
|
|
@ -1058,41 +1054,41 @@ value in return.
|
|
|
|
IMPORTANT: _Functions cannot be recursive in PascaLIGO_, that is why
|
|
|
|
IMPORTANT: _Functions cannot be recursive in PascaLIGO_, that is why
|
|
|
|
loops or iterators are needed.
|
|
|
|
loops or iterators are needed.
|
|
|
|
|
|
|
|
|
|
|
|
### Procedures
|
|
|
|
<!-- ### Procedures -->
|
|
|
|
|
|
|
|
|
|
|
|
WARNING: Procedures are not implemented in the current version of LIGO, they
|
|
|
|
<!-- WARNING: Procedures are not implemented in the current version of LIGO, they -->
|
|
|
|
will appear in a future version with these semantics but cannot currently be
|
|
|
|
<!-- will appear in a future version with these semantics but cannot currently be -->
|
|
|
|
used.
|
|
|
|
<!-- used. -->
|
|
|
|
|
|
|
|
|
|
|
|
Procedures are a special kind of functions that return `Unit`. They
|
|
|
|
<!-- Procedures are a special kind of functions that return `Unit`. They -->
|
|
|
|
are declared as follows:
|
|
|
|
<!-- are declared as follows: -->
|
|
|
|
|
|
|
|
|
|
|
|
procedure my_name ( ... (* parameters here *)) is
|
|
|
|
<!-- procedure my_name ( ... (* parameters here *)) is -->
|
|
|
|
... // local declarations here
|
|
|
|
<!-- ... // local declarations here -->
|
|
|
|
begin
|
|
|
|
<!-- begin -->
|
|
|
|
... // instructions here
|
|
|
|
<!-- ... // instructions here -->
|
|
|
|
end
|
|
|
|
<!-- end -->
|
|
|
|
|
|
|
|
|
|
|
|
Since function calls (see section "Functions") leave the environment
|
|
|
|
<!-- Since function calls (see section "Functions") leave the environment -->
|
|
|
|
invariant, one may wonder what use there is to procedures. As we have
|
|
|
|
<!-- invariant, one may wonder what use there is to procedures. As we have -->
|
|
|
|
seen in the section about "Lists" and their iterators, the exception
|
|
|
|
<!-- seen in the section about "Lists" and their iterators, the exception -->
|
|
|
|
to this rule are predefined iterators, like `list_iter`. They actually
|
|
|
|
<!-- to this rule are predefined iterators, like `list_iter`. They actually -->
|
|
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allow the iterated function to perform side effects. Here is the
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<!-- allow the iterated function to perform side effects. Here is the -->
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example again:
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<!-- example again: -->
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function iter (const delta : int; const l : list (int)) : int is
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<!-- function iter (const delta : int; const l : list (int)) : int is -->
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var acc : int := 0
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<!-- var acc : int := 0 -->
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procedure aggregate (const i : int) is
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<!-- procedure aggregate (const i : int) is -->
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begin
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<!-- begin -->
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acc := acc + i
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<!-- acc := acc + i -->
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end
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<!-- end -->
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begin
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<!-- begin -->
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aggregate (delta); // Has no effect on acc
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<!-- aggregate (delta); // Has no effect on acc -->
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list_iter (l, aggregate) // Has an effect on acc
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<!-- list_iter (l, aggregate) // Has an effect on acc -->
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end with acc
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<!-- end with acc -->
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(For the keen reader, this is because the iterated function is inlined
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<!-- (For the keen reader, this is because the iterated function is inlined -->
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by the compiler.)
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<!-- by the compiler.) -->
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## Instructions
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## Instructions
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@ -1154,7 +1150,7 @@ To iterate on a set `s`, we would write, for instance,
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... // instructions
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... // instructions
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end
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end
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where `e` is bound in turn in increasing orde to each element of the
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where `e` is bound in turn in increasing order to each element of the
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set `s`. For example, given the declarations
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set `s`. For example, given the declarations
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const s : set (int) = set 3; 1; 2 end
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const s : set (int) = set 3; 1; 2 end
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@ -1329,7 +1325,7 @@ PascaLIGO has an explicit keyword for the non-operation: `skip`. Using
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- The `for` loop is not supported yet.
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- The `for` loop is not supported yet.
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- Procedures are not supported yet.
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<!-- - Procedures are not supported yet. -->
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- Nested code blocks are not supported yet.
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- Nested code blocks are not supported yet.
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Christian Rinderknecht