Pair (melange.Stdlib.Pair)

Pairs

type t('a, 'b) = ('a, 'b);

The type for pairs.

let make: 'a => 'b => ('a, 'b);

make a b is the pair (a, b).

let fst: ('a, 'b) => 'a;

fst (a, b) is a.

let snd: ('a, 'b) => 'b;

snd (a, b) is b.

let swap: ('a, 'b) => ('b, 'a);

swap (a, b) is (b, a).

Iterators

let fold: ('a => 'b => 'c) => ('a, 'b) => 'c;

fold f (a, b) applies f to a and b.

let map: ('a => 'c) => ('b => 'd) => ('a, 'b) => ('c, 'd);

map f g (a, b) applies f to a and g to b.

let iter: ('a => unit) => ('b => unit) => ('a, 'b) => unit;

iter f g (a, b) first applies f to a, and then g to b.

let map_fst: ('a => 'c) => ('a, 'b) => ('c, 'b);

map_fst f p applies f to p's first component.

let map_snd: ('b => 'c) => ('a, 'b) => ('a, 'c);

map_snd f p applies f to p's second component.

Predicates and comparisons

let equal: 
  ('a => 'a => bool) =>
  ('b => 'b => bool) =>
  ('a, 'b) =>
  ('a, 'b) =>
  bool;

equal eqa eqb (a1, b1) (a2, b2) is true if and only if eqa a1 a2 and eqb b1 b2 are both true.

let compare: 
  ('a => 'a => int) =>
  ('b => 'b => int) =>
  ('a, 'b) =>
  ('a, 'b) =>
  int;

compare cmpa cmpb is a total order on pairs using cmpa to compare the first component, and cmpb to compare the second component. It is implemented by a lexicographic order.