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I'm in the same boat as you -- here are the two best resources I found:
https://mukulrathi.com/create-your-own-programming-language/...
https://jaked.org/blog/2021-09-07-Reconstructing-TypeScript-...
I read through the first 10 chapters of TAPL, and skimmed the rest. The first 10 chapters were good to remind myself of the framing. But as far as I can tell, all the stuff I care about is stuffed into one chapter (chapter 11 I think), and the rest isn't that relevant (type inference stuff that is not mainstream AFAIK)
This is also good:
https://github.com/golang/example/blob/master/gotypes/README...
And yeah I think we had the same conversation on Reddit -- somebody needs to make a Crafting Interpreters for type checking :) Preferably with OOP and functional and nominal/structural.
I'm planning on doing something similar to what I did for pattern matching [1]: basically building something entirely standalone that fits in 2k LOC or so, and explains the basics (i.e. nominal typing plus basic sub-typing), hopefully such that people can then take that and extend it.
As for _when_ I'll do that, that depends on when I can convince my inner critic to actually commit to the idea :)
[1]: https://github.com/yorickpeterse/pattern-matching-in-rust
Might this help? I wrote it: https://azdavis.net/posts/define-pl-01/
I highly recommend https://github.com/sdiehl/write-you-a-haskell as it is very developer friendly. It’s not complete, but it really gets the gears turning and will set you up for writing your own Hendley-Milner style type checker.
I'm curious how you went. Here's my attempt: https://github.com/chewxy/hm , the core of which (i.e. the interface type) is what powers most of the languages I wrote (different languages I wrote have different unification schemes)
> Aren't languages like C notoriously difficult to parse? I've read that they're actually context sensitive.
All programming languages with identifiers are context-sensitive if you put well-formedness into the grammar. C is not exactly difficult to parse, rather it just needs some specific approach compared to most other languages. The biggest (and technically the only [1]) ambiguity is a confusion between type-specifier and primary-expression, which is a roundabout way to say that `(A) * B` is either a multiplication or a dereference-then-cast expression depending on what `A` is in the current scope. But it also has a typical solution that works for most parsers: parser keeps a stack of scopes with contained identifiers, and lexer will distinguish type identifiers from other identifiers with that information. This approach is so popular that even has a name "semantic feedback".
[1] As an example, the notorious pointer and array declaration syntax is actually an unambiguous context-free grammar. It is notorious only because we humans can't easily read one.
> IIRC much of Go's syntax was designed to avoid parsing complexity.
Go's semantics (in particular, name resolution and module system) was designed to avoid complexity. Its syntax is quite normal, modulo personal and subjective bits which all languages have. I can't see any particular mention of syntax decision to performance in the initial spec document [2].
[2] https://github.com/golang/go/blob/18c5b488a3b2e218c0e0cf2a7d...
Cool to see an implementation in Go, nice! Here's where I got to with my first attempt: https://github.com/cobbweb/flite. There's definitely stuff I'd do a bit different, my second attempt is actually a project to learn Rust with, but I'm already considering switch to Ocaml haha!