z

z.js

var match = []

var _finalizeExpr = function(match) {
  var vs = match[0]
  var _iter = match[1]
  var _done = match[2]
  
  var i = 0
  var _iterWrappper = function() {
    if(i === vs.length) {
      _done()
    }
    else {
      _iter(vs[i], _iterWrappper)
      i++
    }
  }
  
  _iterWrappper()
};

([Array, Fn]
  .map(function(v) {
    return v.prototype
  })
  .forEach(function(v) {
    v.valueOf = function() { var that = this;
      _log(typeof(that))
      if(
        that instanceof Array && match.length === 0
        || that instanceof Fn && match.length === 1
        || that instanceof Fn && match.length === 2
      ) {
        match.push(that)
        if(match.length === 3) {
          _finalizeExpr(match.concat())
          match = []
        }
      }
      else {
        _log('break')
        match = []
      }
    }
  })
);

([1, 2, 3] 
  | function(v, _next) {
    setTimeout(function() {
      _log(v)
      _next()
    }, 1000)
  } 
  | function() {
    _log('end')
  }
)  

Cute hack.