Version: 0.9.0

Map

function empty : map ('key, 'value)

Create an empty map.

type move is int * int
type register is map (address, move)

const empty : register = Map.empty

const empty : register = map []

function literal : list ('key * 'value) -> map ('key, 'value)

Create a non-empty map.

const moves : register =
  Map.literal (list [
    (("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address), (1,2));
    (("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address), (0,3))]);

Alternative way of creating an empty map:

const moves_alternative : register =
  map [
    ("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address) -> (1,2);
    ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address) -> (0,3)];

function find_opt : 'key -> map ('key, 'value) -> option 'value

Retrieve a (option) value from a map with the given key. Returns None if the key is missing and the value otherwise.

const my_balance : option (move) =
  Map.find_opt (("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address), moves)

Alternatively:

const my_balance_alternative : option (move) =
  moves [("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address)];

function update : 'key -> option 'value -> map ('key, 'value) -> map ('key, 'value)

Note: when None is used as a value, the key and associated value is removed from the map.

  const updated_map : register = Map.update(("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address), Some (4,9), moves);

Alternatively:

function update (var m : register) : register is
  block {
    m [("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address)] := (4,9);
  } with m
  

If multiple bindings need to be updated, PascaLIGO offers a patch instruction for maps, similar to that for records.

function assignments (var m : register) : register is
  block {
    patch m with map [
      ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address) -> (4,9);
      ("tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx" : address) -> (1,2)
    ]
  } with m

function add : 'key -> 'value -> map ('key, 'value) -> map ('key, 'value)

const added_item : register = Map.add (("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN" : address), (4, 9), moves)

function remove : 'key -> map ('key, 'value) -> map ('key, 'value)

  const updated_map : register = 
    Map.remove (("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address), moves)

Alternatively, the instruction remove key from map m removes the key key from the map m.

function rem (var m : register) : register is
  block {
    remove ("tz1gjaF81ZRRvdzjobyfVNsAeSC6PScjfQwN": address) from map moves
  } with m

const updated_map : register = rem (moves)

function iter : ((key, value) -> unit) -> map (key, value) -> unit

function iter_op (const m : register) : unit is
  block {
    function iterated (const i : address; const j : move) : unit is
      if j.1 > 3 then Unit else (failwith ("Below range.") : unit)
  } with Map.iter (iterated, m)

Note that map_iter is deprecated.

function map : (('key, 'value) -> ('mapped_key, 'mapped_item)) -> map ('key, 'value) -> map ('mapped_key, 'mapped_value)

function map_op (const m : register) : register is
  block {
    function increment (const i : address; const j : move) : move is
      (j.0, j.1 + 1)
  } with Map.map (increment, m)

Note that map_map is deprecated.

function fold : (('accumulator -> ('key, 'value) -> 'accumulator) -> map ('key, 'value) -> 'accumulator) -> 'accumulator

function fold_op (const m : register) : int is
  block {
    function folded (const i : int; const j : address * move) : int is
      i + j.1.1
  } with Map.fold (folded, m, 5)

Note that map_fold is deprecated.

function size : map ('key, 'value) -> nat

Returns the number of items in the map.

function mem : key -> map (key, value) -> bool

Checks if a key exists in the map.