continuation.js

continuation.js
===============

Continuation support for Node.js

* It converts JavaScript code into Continuation Passing Style (CPS) code in a best effort manner.
* No new syntax or keyword is required.
* Fallback mechanism when CPS is not possible or not implemented.
* Tail calls are properly handled.

How to use
----------

$3

% git clone https://github.com/dai-shi/continuation.js.git
% ./bin/continuation-compile sample/fact.js > cps_fact.js

% cat sample/fact.js
function fact(x) {
function fact_tail(x, r) {
if (x === 0) {
return r;
} else {
return fact_tail(x - 1, x * r);
}
}
return fact_tail(x, 1);
}

% node -e "console.log(require('./sample/fact.js').fact(100000))"

.../continuation.js/sample/fact.js:2
function fact_tail(x, r) {
^
RangeError: Maximum call stack size exceeded

% node -e "console.log(require('./cps_fact.js').fact(100000))"
Infinity

How it works
------------

* 4 classes are defined in the global scope.
* CpsFunction
* CpsContinuation
* CpsResult
* CpsRun
* CPS enabled functions have the CpsEnabled=true property.
* Traversing AST to transform into CPS, only when possible!
* Keeping original code so that non-CPS is always possible.

Limitations
-----------

* There are some overhead, obviously.
* Not all calls are transformed into CPS.
* Arguments objects are handled, but it may cause some problems.
* Maybe some more.

TODOs
-----

* Integrate with Node.js module system.
* Better documents.
* Transform non-tail calls into CPS.
* More tests.
* Avoid duplicating functions.
* Fix ugly code.

Author
------

Daishi Kato @dai_shi