Difference between revisions of "GHC/Type system"
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(typo + new topic per SPJ https://ghc.haskell.org/trac/ghc/ticket/13657#comment:1) |
(fix link to users guide) |
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* '''[[GHC/Stand-alone deriving declarations|"Stand-alone deriving" declarations]]''' |
* '''[[GHC/Stand-alone deriving declarations|"Stand-alone deriving" declarations]]''' |
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* '''[[GHC/TypeSigsAndAmbiguity|Type signatures and ambiguity]]''' |
* '''[[GHC/TypeSigsAndAmbiguity|Type signatures and ambiguity]]''' |
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| − | * '''Overlapping instances'''. GHC supports overlapping instances, with carefully specified rules. Make sure you read the [ |
+ | * '''Overlapping instances'''. GHC supports overlapping instances, with carefully specified rules. Make sure you read the [https://downloads.haskell.org/ghc/latest/docs/html/users_guide/glasgow_exts.html#instance-declarations relevant sections of the user manual]. Here is an application note about [[GHC/AdvancedOverlap|advanced use of overlapping instances]], combined with functional dependencies. |
* '''[[GHC/SuperClass|Super-Class Constraints: Type Families, Type Equalities, FunDep, Overlaps]]''' |
* '''[[GHC/SuperClass|Super-Class Constraints: Type Families, Type Equalities, FunDep, Overlaps]]''' |
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* '''[[GHC/Coercible|Safe coercions using Coercible]]''' |
* '''[[GHC/Coercible|Safe coercions using Coercible]]''' |
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Revision as of 06:11, 23 July 2020
Type system extensions in GHC
GHC comes with a rather large collection of type-system extensions (beyond Haskell 98). They are all documented in the user manual, but this page is a place to record user-oriented observations, notes, and suggestions on how to use them.
- Indexed data types
- Agda-like "holes" in GHC
- "Stand-alone deriving" declarations
- Type signatures and ambiguity
- Overlapping instances. GHC supports overlapping instances, with carefully specified rules. Make sure you read the relevant sections of the user manual. Here is an application note about advanced use of overlapping instances, combined with functional dependencies.
- Super-Class Constraints: Type Families, Type Equalities, FunDep, Overlaps
- Safe coercions using Coercible