rambda/src/pipe.js

Lightweight and faster alternative to Ramda with included TS definitions

import { reduce } from './reduce.js'

export function _arity(n, fn) {
  switch (n) {
    case 0:
      return function () {
        return fn.apply(this, arguments)
      }
    case 1:
      return function (a0) {
        return fn.apply(this, arguments)
      }
    case 2:
      return function (a0, a1) {
        return fn.apply(this, arguments)
      }
    case 3:
      return function (a0, a1, a2) {
        return fn.apply(this, arguments)
      }
    case 4:
      return function (a0, a1, a2, a3) {
        return fn.apply(this, arguments)
      }
    case 5:
      return function (a0, a1, a2, a3, a4) {
        return fn.apply(this, arguments)
      }
    case 6:
      return function (a0, a1, a2, a3, a4, a5) {
        return fn.apply(this, arguments)
      }
    case 7:
      return function (a0, a1, a2, a3, a4, a5, a6) {
        return fn.apply(this, arguments)
      }
    case 8:
      return function (a0, a1, a2, a3, a4, a5, a6, a7) {
        return fn.apply(this, arguments)
      }
    case 9:
      return function (a0, a1, a2, a3, a4, a5, a6, a7, a8) {
        return fn.apply(this, arguments)
      }
    case 10:
      return function (a0, a1, a2, a3, a4, a5, a6, a7, a8, a9) {
        return fn.apply(this, arguments)
      }
    default:
      throw new Error(
        'First argument to _arity must be a non-negative integer no greater than ten',
      )
  }
}

function _pipe(f, g) {
  return function () {
    return g.call(this, f.apply(this, arguments))
  }
}

function pipeFn() {
  if (arguments.length === 0) {
    throw new Error('pipe requires at least one argument')
  }

  return _arity(
    arguments[0].length,
    reduce(
      _pipe,
      arguments[0],
    )(Array.prototype.slice.call(arguments, 1, Number.POSITIVE_INFINITY)),
  )
}

export function pipe(...inputs) {
  const [input, ...fnList] = inputs

  return pipeFn(...fnList)(input)
}