fff-js/general/take.js

Functional javascript lib

import curry from "./curry";
import toIter from "./toIter";
import nop from "./nop";

export default curry(function take(l, iter) {
  if (l === 0) return [];
  let res = [];
  iter = toIter(iter);
  return function recur() {
    let cur;
    while (!(cur = iter.next()).done) {
      const a = cur.value;
      if (a instanceof Promise) {
        return a
          .then(a => (res.push(a), res).length == l ? res : recur())
          .catch(e => e == nop ? recur() : Promise.reject(e));
      }
      res.push(a);
      if (res.length == l) return res;
    }
    return res;
  } ();
});