@stdlib/utils-compose NPM

compose

Function composition.

Installation

npm install @stdlib/utils-compose

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

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.