map/reduce/pipe in 3m

map-reduce-pipe.js

// map, reduce, pipe in 3 minutes

const reduce = (reducer, defaultAcc, list) => {
  let acc = defaultAcc

  for(let item of list) {
    acc = reducer(acc, item)
  }

  return acc
}

reduce((acc, x) => acc + x, 0, [1,2,8]) //?


const map = (func, list) => reduce(
  (acc, item) => {
    acc.push(func(item))
    return acc
  },
  [],
  list
)

map(x => x + 1, [2,2,2]) //?

const pipe = funcs => input => reduce(
  (acc, func) => func(acc),
  input,
  funcs
)

pipe([
  x => x + 'A',
  x => x + 'B'
])('hello ') //?