I was recently thinking a bit about how one could create a typed Forth-like system, by adding a 3rd parallel stack that would hold the type on the data stack, and was used for type checking.

I really wanted to like Forth (which is very similar to Lisp/Smalltalk systems, even possibly more elegant in some respects), because of the system extensibility, but the stack errors drove me crazy. So if the system had the ability to show the types of things on the stack (or name them) while programming, that would be a big help.

Such Forth seems to be surprisingly close to Haskell (or other lambda calculus like language), which I really enjoy lately (I wouldn't go back to Lisp), but written in reverse.