Show HN: Neeilang: Minimalist OOP Language That Compiles to LLVM IR (opens in new tab)

1) LLVM IR is strongly typed, which makes it very challenging to implement a dynamically-typed language on top of it. AFAIK, there aren't many (any?) successful such implementations of dynamically-typed languages. I haven't used other backend libraries, but I do think that looser typing at the IR level would make it a lot harder to catch implementation bugs; at least with LLVM, you are likely to hit an assertion if you break typing rules in the IR.

2) The type-checker is fairly ad-hoc, and I admittedly didn't look much into the literature here. The general idea is that since variable/function/class field types are explicitly typed, every expression can be checked for violating it's expected type. Implementation-wise, this is facilitated using the visitor pattern [1]. For certain expressions, some extra flexibility is allowed - for example, assigning an object of a child class to a variable of the parent class is not a type error.

[1] https://github.com/neeilan/neeilang/blob/master/src/type-che...

Just an itch to understand the tools of the trade better!

Thanks! I've updated the doc to Markdown as suggested by other commenters, so it is now available at https://github.com/neeilan/neeilang/tree/master/doc/Lang.md

To get an interesting unique feature I recommend implementing generic dispatch a la CLOS or Dylan. That also makes your library writing a real joy, for example you can just write a plus function for each combo of types.

Check out Dylan, a high performance dynamic language that compiles to LLVM. Check out this example:

https://opendylan.org/documentation/intro-dylan/multiple-dis...

This is how to do it: https://en.wikipedia.org/wiki/C3_linearization

Gives the language powerful uniqueness feature that the 'mainstream' languages don't have.