partialBinder.js

// If the Partial Application Syntax is not available, use this
// Code by Kusu

const partialBinder = ((hole, rest) => {
  "use strict";
  function partiallyBound(fn, args, ...missing) {
    const argsLen = args.length;
    const missingIter = missing[Symbol.iterator]();
    for (let i = 0; i < argsLen; ++i) {
      switch (args[i]) {
        case hole: break;
        case rest: args.splice(i, 1, ...missing); return fn.apply(this, args);
        default: continue;
      }
      const { done, value } = missingIter.next();
      args[i] = done ? null : value;
    }
    return fn.apply(this, args);
  }
  function partialBinder(fn, ...args) {
    let symbolMask = 0;
    for (const a of args) {
      switch (a) {
       case hole:
        if (symbolMask & 1) break;
        symbolMask |= 0b10;
        continue;
       case rest:
        if (symbolMask & 1) break;
        symbolMask |= 0b01;
       default:
        continue;
      }
      throw new SyntaxError("illegal parameters");
    }

    if (symbolMask) return partiallyBound.bind(this, fn, args);
    else return fn.bind(this, ...args);
  }
  return Object.defineProperties(partialBinder, {
    hole: { value: hole },
    rest: { value: rest },
  });
})(Symbol("hole"), Symbol("rest"));

// partialBinder(console.log, 1, partialBinder.hole, 3)(2, 4)
// 1, 2, 3
// partialBinder(console.log, 1, partialBinder.hole, 3, partialBinder.rest)(2, 4)
// 1, 2, 3, 4

// Partial Application Syntax
// console.log(1, ?, 3)(2, 4)
// 1, 2, 3
// console.log(1, ?, 3, ...)(2, 4)
// 1, 2, 3, 4