# `constraint-tuples`
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[Hackage: constraint-tuples]:
  http://hackage.haskell.org/package/constraint-tuples
  "constraint-tuples package on Hackage"
[Haskell.org]:
  http://www.haskell.org
  "The Haskell Programming Language"
[tl;dr Legal: BSD3]:
  https://tldrlegal.com/license/bsd-3-clause-license-%28revised%29
  "BSD 3-Clause License (Revised)"

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.
* `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, but because this
  requires use of GHC features only present on 8.0 or later, this module does
  not export anything on earlier versions of GHC.