For a -very- primitive Scheme -> Parrot compiler, see http://216.254.0.2/~jgoff/Files/scheme.tar.gz
This is purely proof-of-concept for a much more sophisticated implementation. The current tarball has support for only integer math operators and predicates, although there is minimal support for data types and data type tracing. I'm hoping to use this weekend to add support for real data types and possibly strings. Test files (using the provided version of Test::More) are in the t/ directory, and can be run by typing 'make test' at the command line. The test suite currently covers all of the currently-working expressions. Simple variables will hopefully be added over the weekend alongside data type tracing. My motivation for this little project was to prove that more than one class of languages could easily be targeted to the same set of assembly instructions. LISP and its cousin, Scheme, has a regular syntax, and it was relatively simple to tokenize, unlike Perl or cousins. On a more practical note I'm experimenting with register operations which cross stack boundaries. This would allow compilers to not worry about situations when all 32 I/N/S/P registers are in use, and a temporary is needed. For instance: <reserve I0-I31> # Pretty extreme, but possible with a tight compiler. mark pushi set I1,5 mul I0,I1,I31 # I31 retains its value from the stack-preserving 'push' operation copy_mark I0,I31 # Copy from I0 to I31 at the marked register frame popi # The stack is now back to where it was, with I31 multiplied by 5 Of course, this requires implementation of the 'mark' instruction. (Though it can be emulated by temporarily hardwiring the copy_mark operator to use the register frame just above the current frame) If my explanation isn't clear, then please ask for clarification. I keep hoping that there's an answer to my situation that doesn't involve new instructions, or can be implemented without a great deal of overhead. -Jeff Goff <[EMAIL PROTECTED]>
