iter-tools-es/internal/curry.js

The iterable toolbox

function curry(fn, expectedArgsLength = fn.length, appliedArgs = []) {
  return (...args) => {
    if (expectedArgsLength <= args.length) {
      return fn(...appliedArgs, ...args);
    }

    return curry(fn, expectedArgsLength - args.length, [...appliedArgs, ...args]);
  };
}

exports.curry = curry;

function variadicCurryWithValidationInner(config, args) {
  const {
    fn,
    validateArgs,
    variadic,
    reduces,
    growRight,
    minArgs,
    maxArgs,
    isIterable,
    iterableType,
    applyOnIterableArgs,
    IterableClass
  } = config;

  if (args.length > minArgs) {
    let argsIterable = true;
    const iterableArgsStart = variadic ? args.findIndex((arg, i) => isIterable(arg) && i >= minArgs) : Math.min(maxArgs, args.length - 1);
    const iterableArgsEnd = variadic ? args.length : iterableArgsStart + 1;

    if (variadic) {
      for (let i = iterableArgsStart; i < args.length; i++) {
        argsIterable = argsIterable && isIterable(args[i]);
      }
    } else {
      argsIterable = isIterable(args[iterableArgsStart]);
    }

    if (args.length > maxArgs && (iterableArgsStart === -1 || !argsIterable)) {
      const iterableTypeOrNames = variadic ? `...${iterableType}s` : iterableType;
      const baseMessage = `${fn.name} takes up to ${maxArgs} arguments, followed by ${iterableTypeOrNames}. ` + `You already passed ${args.length} arguments`;

      if (variadic) {
        throw new Error(`${baseMessage} and the following arguments were not all ${iterableType}s`);
      } else {
        throw new Error(`${baseMessage} and the last argument was not ${iterableType}`);
      }
    }

    if (iterableArgsStart >= 0 && argsIterable) {
      for (let i = iterableArgsStart; i < iterableArgsEnd; i++) {
        args[i] = applyOnIterableArgs(args[i]);
      }

      const iterablesArg = variadic ? args.slice(iterableArgsStart) : args[iterableArgsStart];
      args.splice(iterableArgsStart);

      if (!growRight) {
        args.reverse();
      }

      args.unshift(iterablesArg);
      validateArgs(args);
      return reduces ? fn(...args) : new IterableClass(fn, args);
    } else {}
  }

  return variadicCurryWithValidation(config, args);
}

function variadicCurryWithValidation(config, previousArgs = []) {
  return (...args) => {
    if (args.length === 0) {
      throw new Error('Cannot make a partial application with no arguments');
    }

    args.unshift(...previousArgs);
    return variadicCurryWithValidationInner(config, args);
  };
}

exports.variadicCurryWithValidation = variadicCurryWithValidation;