Allow (multi-)pattern matching in 'with val' #1230
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jiribenes
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Nov 28, 2025
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| with val x: Int = foreach([1,2,3]); | ||
| with val (a, b) = bar; | ||
| with val x = foreach([1,2,3]); | ||
| with val a, b = bar; |
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This is a breaking change ^ as type annotations are no longer supported and multiple arguments have to be written without the parenthesis.
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Does it make sense to support else clauses for exhaustive pattern matching?
Like:
with val Some(v) = foo() else do raise()
...
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I don't see a reason why not :)
In an ideal case, I'd like to share as much parser code as possible with destructuring ala val (x, Some(y)) = ... (and with lambda-case)
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Resolves #707
In this PR, we allow more general
with val, specificallywith val <PATTERN> (, <PATTERN>)* = <EXPR>; <STMTS>.This comes at a cost:
with val x: Int = foreach([1,2,3]);becomes unsupported as the: Intis no longer possible (since it's a pattern and those cannot have type annotations right now).