// ramda 0.17.1

import {
  pipe, replace, split, curry, append,
  head, tail, nth, length, map, zipObj,
  values, merge, isArrayLike, apply, filter} from 'ramda'
import fs from 'fs'

const tokenize = pipe(replace(/\(/g, '( '), replace(/\)/g, ' )'), split(/\s+/))

const ast = curry((list, tokens) => {
  if (length(tokens) == 0) {
    return list
  }
  if (head(tokens) == '(') {
    const x = ast([], tail(tokens))
    return ast(append(nth(0, x), list), nth(1, x))
  }
  if (head(tokens) == ')') {
    return [list, tail(tokens)]
  }
  return ast(append(head(tokens), list), tail(tokens))
})

const parse = pipe(tokenize, ast([]))

const evaluate = curry((env, x) => {
  if (!isArrayLike(x)) {
    return env[x]
  }
  if (x[0] === 'def') {
    const [, name, exp] = x
    env[name] = evaluate(env, exp)
    return
  }
  if (x[0] === '#') {
    const [, params, body] = x
    return function() {
      const localEnv = merge(env, zipObj(params, values(arguments)))
      return evaluate(localEnv, body)
    }
  }
  const [name, ...rest] = x
  return apply(evaluate(env, name), map(evaluate(env), rest))
})

const env = {}
const program = fs.readFileSync('program.la', 'utf8')

const result = pipe(parse, map(evaluate(env)))(program)

console.log(result)