prowl VS Forth-in-Charm

Functors can help remove a lot of code duplication. For example, the language I am working on has a big equational unification framework for its type system, and I can compose unifiers easily by making them meet some common specification and tying things together. Without functors, I would need to have callback arguments and extra constants in a bunch of the functions, and each function relevant to each unifier would have to be tied together individually, which would be a terrible mess.

I've been developing a language called Prowl in the discord server. Strings can be concatenated into bigger strings, it turns out you can do the same with programs, and they are related - Prowl is a stack language that uses regex for control flow. It's also kind of a logic language, since regex semantics includes forms of backtracking. The patterns match data instead of strings, like in FP, and then the combinators decide the control flow from there. Eval has a type like Stack -> List Stack, then there are 3 basic operators "cat", "alt", and "intersect" (we use juxtaposition, |, and && as in regex, but it's also >>=, <|>, *> in Haskell) which put code together. While the language is still largely in the design phase, there is a prototype interpreter that is able to run most examples. If this interests you, check out the language tour.

Thank you. [It's very early in the works](https://github.com/UberPyro/prowl/), see [tutorial ](https://uberpyro.github.io/prowl/introduction.html) for more details.

I've been implementing the lessons from my last dogfooding (Forth implemented in Charm): getting the bugs out, and implementing more helpful and interactive error messages, a stack trace, etc, so you can really bang away coding. It's nice.

Implementation of Forth in Charm : https://github.com/tim-hardcastle/Forth-in-Charm