Redex for lambda calc with string cat.
Some testing.
Added subtyping. Cleaned up.
Added subtyping. Cleaned up.
Merge branch 'redex' of https://github.com/jonahkagan/doof into redex
Changed preservation predicate to use subtyping.
Added extendable functional objects.
Added type operators and kinding.
Reorganizing.
Added return type annotations to lambdas.
Replaced incorrect usages of obj with t-obj.
Fixed subtyping rule for strings which wasn't checking patterns.
Cleaned up preservation predicate.
Added string cat to type language.
Fixed incorrect object subtyping. Used pattern reduction in type reduction.
Restricted well-kindedness for t-cat to str types.
Added t-ext to type language.
Cleanup.
Added object fold to reduction and typing.
Added t-fold to type language. Wrote t-trans.