Working contravariant optimizations.
Move function combinators to its own file.
Remove useless comment.
Move any/sc to new file.
Move function combinators to combinators directory.
Make instantiate support sequences.
Minor apply fix.
Make code generation not use field but instead generics.
Make tests all run from tests.rkt and move struct name into syntax class.
Change to definition instead of external.
Remove make-combinator.
Made simple contracts combinators.
Make sc->contract cover more cases.
Compiling version of new constraint logic.
Add generic for making the constraints.
New generic structure.
More or less working non recursive constraints.
Working computation of loop types.
Working computation of constraints.
New recursive calculations working.