mignon

mignon is an implementation of Pixley in C. It compiles under gcc with the -ansi -pedantic flags. The executable on my system (32-bit Linux), after stripping, is a mere 9,680 bytes.

mignon takes its input directly from the command line, rather than reading a file. In practice, to make it read a file, you can say in your shell:

% mignon `cat file.pix`

mignon's parser is resumable (meaning, it uses what are basically continuations, or alternately what is basically a push-down automaton, instead of being built in the manner of recursive descent). One "nice" end result of this is that you can split up your Pixley program amongst the command-line parameters however you like:

% mignon '(cons (quote a) (cons (quote b) (quote ())))'
(a b)
% mignon '(cons (quote a)' '(cons (quote b) (quote ())))'
(a b)

mignon does not have a garbage collector. Since it is not really intended to be a long-running process (one s-expression goes in, another s-expression comes out,) this is not generally a problem in practice. It might become an issue if you try to build a really large tower of Pixley interpreters, however.