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

Module documentation for 0.2.4

This version can be pinned in stack with:lens-action-0.2.4@sha256:55ebdf84f05709e14986a1c550030f9af267ed6a597ff9d144544ab9faf9815e,2432


Hackage Build Status

This package contains combinators and types for working with monadic getters and folds as split off from the original lens package.

Contact Information

Contributions and bug reports are welcome!

Please feel free to contact me through github or on the #haskell IRC channel on

-Edward Kmett


0.2.4 [2019.09.13]

  • Remove the use of cpp-options: -traditional. This should be unnecessary on all versions of GHC that lens supports, as modern GHCs already use -traditional internally during preprocessing. More critically, the use of cpp-options: -traditional breaks profiling builds on GHC 8.8 (see

0.2.3 [2018.01.18]

  • Add an Apply context to the Monoid instance for Effect, allowing lens-action to build against lens-4.16.


  • Add a library dependency for the doctests test suite


  • Revamp Setup.hs to use cabal-doctest. This makes it build with Cabal-2.0, and makes the doctests work with cabal new-build and sandboxes.

  • Migrate to new phantom definition in contravariant

  • Add Control.Lens.Action.Type to exposed-modules list.


  • profunctors-5 and lens-4.10 support

  • Add Control.Lens.Action.Type to exposed-modules list.


  • Initial split from lens package