Higher order versions of Prelude classes

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BSD-3-Clause licensed by Edward A. Kmett
Maintained by Edward A. Kmett

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Higher order versions of Prelude classes to ease programming with polymorphic recursion and reduce UndecidableInstances

See for further discussion of the approach taken here.


  • Add instances for Const
  • Add instances for tuples up to 9

  • Mark Prelude.Extras as Trustworthy

  • Added instances for the types in base where possible


  • Derived Functor, Foldable, and Traversable for Lift1 and Lift2


  • Fixed a broken #ifdef


  • Restructured so users can take advantage of default signatures
Depends on 1 package(full list with versions):
Used by 3 packages in lts-6.35(full list with versions):