compose

Function composition.

Usage

var compose = require( '@stdlib/utils/compose' );

compose( ...fcn )

Returns a composite function. Starting from the right, the composite function evaluates each function and passes the result as an argument to the next function. The result of the leftmost function is the result of the whole.

function a( x ) {
    return 2 * x;
}

function b( x ) {
    return x + 3;
}

function c( x ) {
    return x / 5;
}

var f = compose( c, b, a );

var z = f( 6 ); // ((2*x)+3)/5
// returns 3

Only the rightmost function is explicitly permitted to accept multiple arguments. All other functions are evaluated as unary functions.

function a( x, y ) {
    return (x*5) + (y*3);
}

function b( r ) {
    return r + 12;
}

var f = compose( b, a );

var z = f( 4, 6 );
// returns 50

Notes

  • The function will throw if provided fewer than 2 input arguments.

Examples

var compose = require( '@stdlib/utils/compose' );

function a( x, y ) {
    return x * y;
}

function b( z ) {
    return z + 5;
}

function c( r ) {
    return r / 10;
}

var f = compose( c, b, a );

var v = f( 5, 3 );
// returns 2