Abstract pattern synonyms (for hsig and hs-boot)
Most declaration forms (data types, values, type families, etc) support forward declaration in hs-boot/hsig files. However, pattern synonyms do not. This seems like a major omission!
Some problems to solve:
- The obvious syntax
pattern Foo :: pat_tyis insufficient to specify whether or not a pattern is bidirectional or unidirectional. How should this be represented syntactically? - What is the interaction with bundling? Should it be possible to export a bundle of abstract pattern synonyms, with the intent that this means an implementation must also have bundled them together
- See also #12717; abstract pattern synonym should be implementable with a plain old constructor
Trac metadata
| Trac field | Value |
|---|---|
| Version | 8.2.1 |
| Type | FeatureRequest |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler (Type checker) |
| Test case | |
| Differential revisions | |
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| Blocking | |
| CC | |
| Operating system | |
| Architecture |