Swim-scheme is a project mainly written in SCHEME and C++, it's free.
Scheme compiler/interpreter
This is an in-progress attempt to follow and expand on Abdoulaziz Ghuloum in his paper "An Incremental Approach to Compiler Construction". It currently generated (badly) x86 Windows code. I am planning to potentially add some ATmega328 (Arduino) code.
I will just use it as a starting point to experiment on some things and potentially expand on something more meaningful (to me).
Right now the file 'compiler.scm' (in racket scheme) generates x86 Windows code wherever specified from a given scheme expression. This assembly code can be embedded as is (and compiled w/ NASM) in Visual Studio.
A cpp project has been added that contains a "driver" executable that links w/ the generated assembly code and calls it.
Part of the things I have been "working" on during my spare time are programming language structure in general, byte-code interpretation, efficient interpretation, Forth related threaded-code techniques, etc. Ideally I would love to see all this stuff combined in one project (if possible).
This is a long term goal. What I have in mind would be a Forth like interpreter in a subset of Scheme as close as possible to R5RS (which is already a daunting task).