fibonacci bf generate code

bf_gen_fibonacci.js

// code that generates BF (hardcoded) solution using js
// https://www.codewars.com/kata/bf-n-th-fibonacci-number/train/bf

const MAX = 100;
const flag = '+>';
const inp = ',';

const nestedLoop = n => {
  if (n > MAX) return '';
  return `-[
    ${nestedLoop(n+1)}
  ]
  < [[-] > ${int2bf(fib(n))} [-] <] > 
  `;
};

const int2bf = i => {
  return (i+'').split``.reduce(([mem, res], d) => {
    const code = d.charCodeAt();
    const dist = code - mem;
    const sign = dist < 0 ? '-' : '+';
    return [code, [...res, sign.repeat(Math.abs(dist)) + '.']];
  }, [0, []])[1].join``;
};

const fib = (() => {
  const map = new Map();
  return n => {
    if (n in map) return map[n];
    if (n === 1) return 1n;
    if (n === 2) return 1n;
    return map[n] = fib(n-1) + fib(n-2);
  };
})();

console.log([
  flag, inp,
  '[', nestedLoop(1), ']'
].join`\n`.replace(/[^\+\-\<\>\[\]\,\.]/g, ''));