Support refutable sub-patterns in tuple and struct destructuring#600
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Support refutable sub-patterns in tuple and struct destructuring#600
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…et/matches Transform literal sub-patterns (int, bool, char, string) inside tuple and struct patterns into guard conditions during the lower phase (TIR→TIR). For example, `[a, 10] => body` becomes `[a, __lit_N] && __lit_N == 10 => body`. - Parser: extend parse_let_pattern() with literal patterns, rest (..) in tuples, and mut bindings; recognize [bracket as variant pattern start for if-let - Lower: add extract_literal_sub_patterns() to replace literals with temp bindings and build equality guards; handle both Match and IfLet uniformly - String equality uses String^Eq::eq method call; primitives use binary == - Remove float literal test cases (float patterns explicitly rejected by design) Resolves TODO tests: struct_destruct_literal, tuple_destruct_literal https://claude.ai/code/session_01TnBQtMkKForC5jzEJ6Z3Yy
Extend the refutable sub-pattern extraction in the lower phase to handle
variant and enum patterns inside tuple (and struct) match arms, not just
literals. This enables patterns like `match [a, b] { [Bool(x), Bool(y)] => ... }`.
- Rename extract_literal_sub_patterns → extract_refutable_sub_patterns
- Add variant sub-pattern extraction with VariantTest guards and payload binding
- Add enum sub-pattern extraction with discriminant comparison guards
- Handle ref-peeling (deref) for variant/enum sub-patterns in reference contexts
- Add e2e test for variant patterns in tuple destructuring
- Simplify core:json_value Value::eq using the new tuple variant pattern syntax
https://claude.ai/code/session_01TnBQtMkKForC5jzEJ6Z3Yy
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⚠️ Performance Alert ⚠️
Possible performance regression was detected for benchmark.
Benchmark result of this commit is worse than the previous benchmark result exceeding threshold 1.30.
| Benchmark suite | Current: d75ccb5 | Previous: 3b14015 | Ratio |
|---|---|---|---|
sieve (-O1) |
207 ms |
157 ms |
1.32 |
This comment was automatically generated by workflow using github-action-benchmark.
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Summary
This PR adds support for refutable sub-patterns (literals, variants, and enums) within tuple and struct destructuring patterns in match expressions and if-let statements. Previously, only irrefutable patterns like bindings and wildcards were supported in nested positions.
Key Changes
Pattern Extraction Logic (
wado-compiler/src/lower/pattern.rs):pattern_has_refutable_sub_patterns()to detect when a tuple/struct pattern contains refutable sub-patternsextract_refutable_sub_patterns()to transform refutable sub-patterns into guard conditions and body prefix statementsextract_refutable_sub_pattern()to handle individual refutable patterns (literals, variants, enums) by:literal_eq_condition(),get_case_index(), andget_struct_fields()to support pattern extractionParser Updates (
wado-compiler/src/parser.rs):is_pattern_start()to recognize tuple patterns starting with[parse_let_pattern()to support literal patterns in match/if-let contexts (previously only allowed in let bindings)Test Fixtures:
tuple_destruct_variant.wado- tests tuple destructuring with variant sub-patternstuple_destruct_literal.wado- tests tuple destructuring with literal sub-patternsstruct_destruct_literal.wado- tests struct destructuring with literal sub-patternstuple_destruct_literal.wadoandstruct_destruct_literal.wadoto remove unsupported float literal patternsDocumentation Updates:
docs/spec.mdto document nested sub-patterns in tuples and structsdocs/cheatsheet.mdwith examples of nested pattern matchingLibrary Updates (
lib/core/json_value.wado):Value::eq()implementation to use tuple destructuring with variant sub-patternsImplementation Details
The transformation works by:
&&This approach maintains the semantics of pattern matching while enabling more expressive destructuring patterns.
https://claude.ai/code/session_01TnBQtMkKForC5jzEJ6Z3Yy