Because I'm lazy and mixfix w/ proxies is slow

infix.js

var isWrapper = Symbol('isWrapper');

function _(arg, args=[], ops=[]) {
  const myArgs = args.concat([arg]);
  const myOps = ops.slice(0);

  const f = ([op]) => (
    myOps.push(op),
    wrap(arg2 => _(arg2, myArgs, myOps), myArgs, myOps)
  );

  Object.keys(_).forEach(n => {
    Object.defineProperty(f, n, {
      get: () => f([n])
    });
  });

  return wrap(f, myArgs, myOps);
}

var wrap = (f, args, ops) => {
  Object.defineProperty(f, '_', {
    get: () => runProgram(args.slice(0), ops.slice(0))
  });
  Object.defineProperty(f, isWrapper, {
    value: true
  });
  return f;
};

//  apply :: ((a => b), a) => b
var apply = (f, a) => f(a);

//  applyArgs :: Array Any => (Any, String) => Any
var applyArgs = args => (result, c) => {
  // unbox
  if (result[isWrapper]) result = result._;
  result = _[c] (result);

  if (args.length > 0) {
    // unbox
    var arg = args.shift();
    if (arg[isWrapper]) arg = arg._;

    return result (arg);
  }

  return result;
};

//  runProgram :: Program => Any
var runProgram = (args, calls) => calls.reduce(applyArgs(args), args.shift());

//  mixfix :: Array String => Function => Function
var infix = ([pattern]) => f => _[pattern] = f;

//  importLib :: StrMap Function => Effect Unit
var importLib = lib => Object.keys(lib).forEach(k => {
  if (_[k] == null
      && typeof lib[k] === 'function'
      && lib[k].length === 2) {
    _[k] = lib[k];
  }
});

// map :: (a => b) => Array a => Array b
infix `map` (f => xs => xs.map(f));

// ap :: Array (a => b) => Array a => Array b
infix `ap` (fs => xs => fs.reduce((acc, f) => acc.concat(xs.map(f)), []));

_(x => y => x + y)`map`([1,2,3])`ap`([4,5,6])._;

// pipe :: a => (a => b) => b
infix `pipe` (x => f => f(x));

//  inc :: Number => Number
var inc = x => x + 1;

_(0)
  .pipe(inc)
  .pipe(inc)
  .pipe(inc)._; // 3

infix `` (xs => ys => xs.concat(ys));
_([1,2,3]) `` ([4,5,6])._;

infix `$` (_.map);
infix `*` (_.ap);

_(x => y => z => x + y + z) `$` ([1,2,3]) `*` ([4,5,6]) `*` ([7,8,9])._;