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A Common Lisp compiler, designed to compile to C (and from there to native code or JavaScript)
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owlisp is a compiler that compiles Common Lisp to native binaries or JavaScript. To do that, it generates C code from Lisp and then compiles that C code to native binaries, using your C compiler, or emscripten to compile to JavaScript.


For the current status of this project as well as ideas and thoughts that I have about it, please take a look at my blog:

and follow the #owlisp twitter account:


owlisp is not even alpha yet ;) :

  • it does not yet support all language features; currently supported lisp features (in their very basic form) include:
    • constant integers, e.g. 22
    • anonymous functions, e.g. (lambda () 1)
    • named functions, e.g. (defun myfn () 1)
    • variable declarations & references (only lexically scoped), e.g. (lambda (a) a)
    • function application, e.g. (myfn)
  • it is still a lisp-1 (meaning, that it does not use separate namespaces for variable vs. function bindings


I created this project for my own mere fun and because I was searching for something that could translate Common Lisp to JavaScript. This would allow me to write even the client side code of web applications in Lisp.

Why compile to C then? Well, once this can be done, one can use LLVM to compile from C to JavaScript. Actually, this can already be done. When building owlisp, it will search for emscripten. If it is found, you will be able to compile from Common Lisp to JavaScript.

I can only work in my spare time on this project, so don't expect a quick progression on this project.

Feedback is always welcome!


For building it

For building owlisp, you need:

  1. CMAKE (Version >= 2.8)

  2. C compiler (e.g. gcc or clang)

  3. A working common lisp (currently, only SBCL will work) with the packages ASDF, CFFI & APPLY-ARGV available.

  4. (optional) emscripten in order to be able to compile to JavaScript.

For running it

For running owlisp (i.e. compile Common Lisp source code to binaries), you need prerequisites 2 and optionally 4 from above, as well as the owlisp compiler toolchain of course.


Building & installing owlisp

  1. Link the file owlisp.asd to wherever your asdf search path is.

  2. cd into the root directory of owlisp.

  3. Do a mkdir build && cd build.

  4. Do a cmake ... This will generate Makefiles that are tailored specifically for your system. You might want to define an installation prefix: cmake -DCMAKE_INSTALL_PREFIX=/my/installdir ..

  5. Do a make. This will do several things:

    • compile the owlisp compiler binaries & toolchain
    • build a static runtime library (libowlisprt.a) that will be linked to any Lisp program that you compile with owlisp.
  6. Do a make install. This will install the compiler toolchain as well as the runtime library, the to your installation prefix (or the cmake default installation prefix).

  7. Try it, e.g. create a file (e.g. test.lisp) with the following contents:

    (defun myfn (a b)
    (defun main ()
       (myfn 11 22))

    Note that you must defun a function called main. This will be the entry point for your program when you run it. Compile the file by invoking owlisp:

    $ /path/to/owlisp/bin/owlisp -o test test.lisp

    Run it:

    $ ./test

    This example probably won't print much output, but it should at least run successfully :) .

  8. If you have built owlisp with emscripten support, you can try compiling to JavaScript. Do the same as in step 7, but as compile command, issue a

    $ /path/to/owlisp/bin/owlisp -o test.js test.lisp

    I.e. suffixing the name of the output file with .js will cause owlisp to target JavaScript instead of C. You can run it for example with NodeJS:

    $ node test.js
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