Gambit Scheme без gcc?

попробуй :)

# Portability. Because the system is mostly written in Scheme and the compiler generates portable C code, it is easy to port the system as well as programs compiled with it to any platform with a decent C or C++ compiler. There is no reliance on a particular C compiler, although the system can take advantage of some gcc-specific constructs. The C code generated is oblivious to the endianness and word size of the target environment (32 and 64 bit architectures are currently supported).

http://dynamo.iro.umontreal.ca/~gambit/wiki/index.php/Main_Page

Например, google://Gambit+Scheme+tcc

И ещё вот - http://jlongster.com/blog/2009/06/17/write-apps-iphone-scheme/ - там GCC, но видно, что переменная окружения CC выставляется - можно туда что угодно засунуть (лишь бы эти advantage of some gcc-specific constructs работали в другом компиляторе).