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Hi HN! I’ve been working on this language for about 4 months now. While not “complete”, it does have a number of nice features like virtual functions, type inf

Hi HN! I’ve been working on this language for about 4 months now. While not “complete”, it does have a number of nice features like virtual functions, type inference, etc. I reckon it will not be truly useful until GC is added, and that’s what I’m currently working on. Any feedback is welcome and appreciated!

jdmoreira 7y ago
I think it’s great that more and more people are spending time working on programming languages. I have a few questions for you about the type system / type checking. Does llvm make it easier to implement a statically type language than other backends? For example luajit? And how did you learn to implement the typechecker? Is it algorithm W?
- neeeeees 7y ago
  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-checker.cc https://github.com/neeilan/neeilang/blob/master/src/type-che...
dilap 7y ago
What's the motivation? Just a personal itch, or is there something special you're hoping to achieve?
- neeeeees 7y ago
  Just an itch to understand the tools of the trade better!

jdmoreira 7y ago

I think it’s great that more and more people are spending time working on programming languages. I have a few questions for you about the type system / type checking. Does llvm make it easier to implement a statically type language than other backends? For example luajit? And how did you learn to implement the typechecker? Is it algorithm W?

neeeeees 7y ago
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-checker.cc https://github.com/neeilan/neeilang/blob/master/src/type-che...

dilap 7y ago

What's the motivation? Just a personal itch, or is there something special you're hoping to achieve?

neeeeees 7y ago
Just an itch to understand the tools of the trade better!