Functions on functions, creating functions from simpler inputs.
(Most commonly used when programming in functional style using higher-order functions.)
public func compose<A, B, C>(f : B -> C, g : A -> B) : A -> C
Import from the base library to use this module.
motoko name=import
import { compose; const; identity } = "mo:base/Func";
import Text = "mo:base/Text";
import Char = "mo:base/Char";
The composition of two functions f
and g
is a function that applies g
and then f
.
Example:
motoko include=import
let textFromNat32 = compose(Text.fromChar, Char.fromNat32);
assert textFromNat32(65) == "A";
public func identity<A>(x : A) : A
The identity
function returns its argument.
Example:
motoko include=import
assert identity(10) == 10;
assert identity(true) == true;
public func const<A, B>(x : A) : B -> A
The const function is a curried function that accepts an argument x
,
and then returns a function that discards its argument and always returns
the x
.
Example:
motoko include=import
assert const<Nat, Text>(10)("hello") == 10;
assert const(true)(20) == true;