[Haskell-cafe] Use cases of empty type classes
tomtau at connect.hku.hk
Tue Mar 8 06:10:33 UTC 2016
I have one question. What are current use cases of type classes with no methods?
I saw early uses in type-level programming (e.g. HList ).
In the OO world, interfaces with no methods are called marker interfaces -- their use cases range from things that could be done with datatype generic programming in Haskell (e.g. serialization) to metadata annotations (e.g. RandomAccess ).
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