Scheme-to-C

This is a tiny nanopass compiler for compiling a small subset of Scheme to C. It was developed to be presented at Clojure Conj 2013, in Alexandria, VA. It has been a little over a week and half since I started working on it and I've added more documentation and more tests since Clojure Conj.

There is still much to be done. More tests are needed and a few passes are still not documented, and I still have not tested the boehm collector, though I hope to do so soon.

Bartlett's Scheme->C

This should not be confused with Bartlett's Fabled Scheme->C compiler, available at http://scheme2c.alioth.debian.org/, with a clone of the source repository at https://github.com/barak/scheme2c/. (Nod to @barak for pointing this out!)

Required Libraries

There are two required git repositories to run this compiler. This repository (of course), and the nanopass framework repository at https://github.com/nanopass/nanopass-framework-scheme/.

You will also need one of the supported host compilers listed in the next section.

Supported Host Compilers

The current version supports three host compilers: Chez Scheme, Ikarus, and Vicare. All three share similar features that are needed by the Nanopass Framework in order to operate.

Getting Chez Scheme

Chez Scheme is available at http://github.com/cisco/ChezScheme/ with documentaton at http://cisco.github.io/ChezScheme/.

Running on Chez Scheme

In the scheme-to-c directory start scheme using the --libdirs command line switch to tell scheme where to find the nanopass-framework-scheme directory:

$ scheme --libdirs .:<path to nanopass-framework-scheme>
Chez Scheme Version 9.4.1
Copyright 1984-2016 Cisco Systems, Inc.

> (import (c))
> (my-tiny-compile '(+ 4 5))
9

You can run the tests as:

$ scheme --libdirs .:<path to nanopass-framework-scheme>
Chez Scheme Version 9.4.1
Copyright 1984-2016 Cisco Systems, Inc.

> (import (tests))
> (run-tests)
running test 0:
0
passed
running test 1:
-5
passed
  .
  .
  .

Getting Ikarus

Ikarus is no longer under active development, but it is easier to install on a Mac OS X machine than Vicare, so I recommend it if you are on a Mac. You can find Ikarus at https://launchpad.net/ikarus and you can download it using bzr. The easiest way to install it is to use the c64 install script. This installs it into the $HOME/.opt64 subdirectory and you can add $HOME/.opt64/bin to the path to run ikarus.

Running on Ikarus

When running on ikarus you will also need to add the nanopass-framework-scheme directory to the path in order to run the new compiler. This can be done with an environment variable, but I generally find it easier to do this on the ikarus REPL as follows:

$ ikarus 
Ikarus Scheme version 0.0.4-rc1+, 64-bit (revision 1870, build 2013-10-16)
Copyright (c) 2006-2009 Abdulaziz Ghuloum

> (library-path (cons "../nanopass-framework-scheme" (library-path)))
> (import (c))
> (my-tiny-compiler '(+ 4 5))
9

You can also run the tests through ikarus as follows:

$ ikarus 
Ikarus Scheme version 0.0.4-rc1+, 64-bit (revision 1870, build 2013-10-16)
Copyright (c) 2006-2009 Abdulaziz Ghuloum

> (library-path (cons "../nanopass-framework-scheme" (library-path)))
> (import (tests))
> (run-tests)
running test 0:
0
passed
running test 1:
-5
passed
  .
  .
  .

Getting Vicare

Vicare Scheme is a fork of Ikarus that is currently under development. You can find Vicare at http://marcomaggi.github.io/vicare.html. This can be installed using the standard GNU style configure script. The only features we require is posix support, since we need the system call to shell out to run gcc.

Running on Vicare

Similar to Ikarus and Chez Scheme, Vicare also needs to be informed of where to find the nanopass-framework-scheme directory. Vicare also needs to be told to look for additional Scheme file extensions, since I am using .ss instead of the more recently introduced .sls for R6RS Scheme libraries. Here we can use the --more-file-extensions and two calls to the --search-path command line flag, one to search in the nanopass-framework-scheme directory and one in the current directory, ., which is otherwise not included.

$ vicare --more-file-extensions \
--search-path ../nanopass-framework-scheme \
--search-path .
Vicare Scheme version 0.3d1, 64-bit
Revision no-branch/no-commit
Build 2013-10-15

Copyright (c) 2006-2010 Abdulaziz Ghuloum and contributors
Copyright (c) 2011-2013 Marco Maggi

vicare> (import (c))
vicare> (my-tiny-compile '(+ 4 5))
9

We can also run the tests under Vicare as:

$ vicare --more-file-extensions \
--search-path ../nanopass-framework-scheme \
--search-path .
Vicare Scheme version 0.3d1, 64-bit
Revision no-branch/no-commit
Build 2013-10-15

Copyright (c) 2006-2010 Abdulaziz Ghuloum and contributors
Copyright (c) 2011-2013 Marco Maggi

vicare> (import (tests))
vicare> (run-tests)
running test 0:
0
passed
running test 1:
-5
passed
  .
  .
  .

More To Do

• start better documentation of code
• add tests for the compiler
• test on Chez, Ikarus, and Vicare
• test the Boehm garbage collector
• add more and larger tests
• improve the testing framework to allow for quieter output and errors
• add predicates for fixnum and procedure
• finish documentation of code