contravariant

Contravariant functors

http://github.com/ekmett/contravariant/

Version on this page:1.2@rev:1
LTS Haskell 23.19:1.5.5
Stackage Nightly 2025-04-30:1.5.5
Latest on Hackage:1.5.5

See all snapshots contravariant appears in

BSD-3-Clause licensed by Edward A. Kmett
Maintained by Edward A. Kmett
This version can be pinned in stack with:contravariant-1.2@sha256:68bffb9f8c3d0c7a668f2a67c87574fa0b7ab8344c28f868e7a934217fa7eae5,1492

Module documentation for 1.2

  • Data
    • Data.Functor
      • Data.Functor.Contravariant
        • Data.Functor.Contravariant.Compose
        • Data.Functor.Contravariant.Divisible

Contravariant functors

Changes

1.1.1

  • Added Data.Functor.Contravariant.Applicative

1.0

  • Removed Day convolution. The right adjoint of Day convolution is in kan-extensions as the right Kan lift. Moving these there to avoid forcing orphan instances. It also rather dramatically reduces the number of extensions required.
  • This requires a first digit bump as it breaks several of my own packages.

0.6.1.1

  • Fixed issue with needing KindSignatures on older GHCs

0.6.1

  • Added covariant Day convolution. It isn’t contravariant, but it is inspired by the contravariant construction.

0.5.1

  • transformers 0.4 compatibility

0.5

  • Added (>$)
  • Added instances for GHC.Generics

0.4.4

  • Fixed compatibility with GHC 7.7 and tightened Safe Haskell support.

0.4.1

  • Added Day convolution under Data.Functor.Contravariant.Day.

0.3

  • Added Backwards and Reverse instances for transformers 0.3
  • Added instance (Functor f, Contravariant g) => Contravariant (Compose f g). (This is non-canonical, but is necessary to support other packages.)
  • Added Functor instances to ComposeFC and ComposeCF for use when modeling phantom type parameters caused mixing Functor + Contravariant.