fp-lib

fp-lib.js

function curry(arity, fn) {
  return (function nextCurried(prevArgs) {
    return function curried(nextArg) {
      var args = prevArgs.concat([nextArg]);
      if (args.length >= arity) {
        return fn(...args);
      } else {
        return nextCurried(args);
      }
    };
  })([]);
}

function compose(...fns) {
  return pipe(...fns.reverse());
}

function pipe(...fns) {
  return function piped(result) {
    for (let fn of fns) {
      result = fn(result);
    }
    return result;
  };
}

function mapObj(mapperFn, o) {
  var newObj = {};
  var keys = Object.keys(o);
  for (let key of keys) {
    newObj[key] = mapperFn(o[key]);
  }
  return newObj;
}

function filterObj(predicateFn, o) {
  var newObj = {};
  var keys = Object.keys(o);
  for (let key of keys) {
    if (predicateFn(o[key])) newObj[o[key]] = o[key];
  }
  return newObj;
}

function reduceObj(reducerFn, initialValue, o) {
  var result = initialValue;
  var keys = Object.keys(o);
  for (let key of keys) {
    result = reducerFn(result, o[key]);
  }
  return result;
}

function pathOr(or, arrPath, obj) {
  if (!arrPath.length || !obj) return or || "";

  return arrPath.reduce((accObj, value) => {
    if (typeof accObj === "object" && value in accObj) {
      return accObj[value];
    }
    return or;
  }, obj);
}

function functor(value) {
    return {
        map: identity(fn => fn(value)),
        fold: fn => fn(value),
        log: () => `log: ${value}`
    }
}