ML-Projects is a project mainly written in ..., it's free.
Some smaller ML projects modeling different math and CS concepts
These are some different projects I've done in the functional programming language ML while I was in school.
http://www.smlnj.org/
Most model different discrete mathematical concepts like groups, lattices, trees, etc...
I doubt everything works. I think most are syntactically correct, and most should work, though I haven't documented what example input looks like on each function. Perhaps you may find this useful, or at least intriguing.