Ahhh righto! Hehe, I'm so excited! Super interested to see what you've all learned.
Specifically atm I'm learning about in Top-Down Operator Precedence (Pratt) parsing and wondering if it's the right approach to be making. Having extensible syntax would be nice!
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Yep, we're still doing Pratt parsing! Only realistic alternative I'm aware of is Isabelle's Early parsing, but having to specify a formal, context-free priority grammar is pretty far from our approach of "everything goes" parser combinators.
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I've seen GLR, but not investigated too deeply! That's what tree-sitter uses, right? tree-sitter.github.io/tree-sitter/
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I was starting on a hand-rolled parser because over the LR parser generator I was using because `(x : A) -> B` is ambiguous. It could either be parsed as:
- a dependent function type
- a non-dependent function with the input type annotated
I want to prioritise the former.
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Do you have a pointer to the grammar ? Would be interesting as a case for priorities in SDF3
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This is the grammar that they tend to use:
term ::= var
| term term
| "(" term ")"
| term ":" term
| term "->" term
| ( "(" var+ ":" term ")" )+ "->" term
Coming up with good precendences is left as an exercise 😊
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I have an issue for it here: github.com/pikelet-lang/p
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Replying to @brendanzab
seems like the real issue is overloading of parens!
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Looks like an inherent ambiguity that is not solvable by priorities, since those select between a re-ordering of the tree using the same productions. Will do an experiment with SDF3
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Yeah, intuitively I'd expect the dependent type to have priority over the type annotation, but I can't see how that could be gleaned from the grammar alone.
Heh, that's at least what I'm doing for now in github.com/brendanzab/rus - I just do `Fun (A : Type) -> A -> A`
