@hackage / constraint-tuples

constraint-tuples

This library provides classes and type aliases that emulate the behavior of GHC's constraint tuple syntax. Unlike GHC's built-in constraint tuples, the types in this library can be partially applied.

This library exposes four different modules that provide essentially the same API with slight differences in their implementation:

• Data.Tuple.Constraint: A CTupleN class compiles to a dictionary data type with N fields. (When building with GHC 9.10 or later, this will simply re-export the constraint tuples offered by GHC.Classes.)
• Data.Tuple.Constraint.ClassNewtype: A CTupleN class compiles to a newtype around the corresponding built-in constraint tuple type with N arguments.
• Data.Tuple.Constraint.TypeFamily: A CTupleN type alias is a constraint tuple type constructor with N arguments obtained by way of a type family. This will compile to a built-in constraint tuple, but casted with a type family axiom.
• Data.Tuple.Constraint.TypeSynonym: A CTupleN type alias is a constraint tuple type constructor with N arguments obtained by way of a type synonym. This will compile directly to a built-in constraint tuple.