Official Parenscript repository:
Common Lisp Emacs Lisp
Latest commit bc3ba1d Mar 17, 2016 @jasom jasom Merge pull request #28 from TatriX/master

What is Parenscript?

Parenscript is a translator from an extended subset of Common Lisp to JavaScript. Parenscript code can run almost identically on both the browser (as JavaScript) and server (as Common Lisp).

Parenscript code is treated the same way as Common Lisp code, making the full power of Lisp macros available for JavaScript. This provides a web development environment that is unmatched in its ability to reduce code duplication and provide advanced metaprogramming facilities to web developers.


(ql:quickload :parenscript)

or download the latest release


What's the difference?

Parenscript is different from almost all other "language X" to JavaScript translators in that it imposes almost no overhead:

No runtime dependencies

Any piece of Parenscript code is runnable as-is. There are no JavaScript files to include.

Native types

Parenscript works entirely with native JavaScript datatypes. There are no new types introduced, and object prototypes are not touched.

Native calling convention

Any JavaScript code can be called without the need for bindings. Likewise, Parenscript can be used to make efficient, self-contained JavaScript libraries.

Readable code

Parenscript generates concise, formatted, idiomatic JavaScript code. Identifier names are preserved. This enables seamless debugging in tools like Firebug.


Parenscript introduces minimal overhead for advanced Common Lisp features. The generated code is almost as fast as hand-written JavaScript.



BSD (see COPYING file)