Func

Functions on functions, creating functions from simpler inputs.

(Most commonly used when programming in functional style using higher-order functions.)

Import from the core package to use this module.

motoko name=import
import Func = "mo:core/Func";

`public func compose<A, B, C>(f : B -> C, g : A -> B) : A -> C`

The composition of two functions f and g is a function that applies g and then f.

Example:

motoko include=import
import Text "mo:core/Text";
import Char "mo:core/Char";

let textFromNat32 = Func.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 Func.identity(10) == 10;
assert Func.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 Func.const<Nat, Text>(10)("hello") == 10;
assert Func.const(true)(20) == true;