composeN.js

var combinators = require('fantasy-combinators')

var compose = combinators.compose
var identity = combinators.identity
var flip = combinators.flip

var add = function (a) {
  return function (b) {
    return b + a
  }
}

var mul = function (a) {
  return function (b) {
    return b * a
  }
}

var uncurry2 = function (f) {
  return function (a, b) {
    return f(a)(b)
  }
}

var reduce = function (reducer) {
  return function (xs) {
    return function (initial_val) {
      return xs.reduce(uncurry2(reducer), initial_val)
    }
  }
}

var compose_n = flip (reduce (compose)) (identity)

// f(x) = 2(5x + 3) = mul(2)(add(3)(mul(5)(x)))
var derp = compose_n ([mul(2), add(3), mul(5)])

// 56
console.log(derp(5))