I wrote a couple of blog posts a few years back about RPython (http://www.maori.geek.nz/post/rpython_compiling_python_to_c_for_the_speed http://www.maori.geek.n

I wrote a couple of blog posts a few years back about RPython (http://www.maori.geek.nz/post/rpython_compiling_python_to_c_for_the_speed http://www.maori.geek.nz/post/rpython_compiling_python_to_c_... http://www.maori.geek.nz/post/rpython_is_not_a_language_an_introduction_to_the_rpython_language http://www.maori.geek.nz/post/rpython_is_not_a_language_an_i...) where I implemented a Boolean Satifiability Solver in it. The biggest problem with RPython is there is no definition of a language, it is a tool chain, and it can get very difficult to tell whether what you are writing will even compile. It was very fast though.