serial loop support

[guileen]

var a;
for(var i=0; i < 100; i++){
  a = foo(a, _);
}
console.log(a);

compile to serial loop

target code 1

var a, i=0;
function next(){
  foo(a, function(err, _a){
   if(err) return cb(err);
   a = _a;
   i++;
   if(i<100){
      next();
    } else {
      console.log(a);
    }
  }
}
next();

target code 2

var a;
function next(i, after){
  foo(a, function(err, _a){
   if(err) return cb(err);
   a = _a;
   if(i<100) next(++i);
   else after()
  }
}
function after(){
  console.log(a);
}
next(0, after);

which one is better?

[guileen]

for(var i = 0;i<100;i++){
  a+=i;
  b = foo(a, _);
}

loop_block readed a, and updated a, but not update a in async mode, so, next a do not need to wait previous foo callback.

for(...){
  a = foo(_);
  b = bar(a, _);
}

a is readed and updated, but foo can be parallel, a=_a;b=bar(a, _); can be execute one after another

for(...){
  a = foo(b, _);
  b = bar(a);
}

foo depends b depends a depends foo, so foo depends foo, this should be serial...

what is the key logic...

for(...){
  a = foo(b, _);
  b = bar(_);
}

foo depends b depends bar of pervious loop

[guileen]

also take care for(var i..) res.push(foo(i, _));, the single statement without {}

[fengmk2]

next() 是递归？

[guileen]

是递归