microlens support for Reader/Writer/State from mtl http://github.com/monadfix/microlens

This package is not currently in any snapshots. If you're interested in using it, we recommend adding it to Stackage Nightly. Doing so will make builds more reliable, and allow stackage.org to host generated Haddocks.

BSD-3-Clause licensed by Edward Kmett, Artyom Kazak
Maintained by Monadfix

This package contains functions (like view or +=) which work on MonadReader, MonadWriter, and MonadState from the mtl package.

This package is a part of the microlens family; see the readme on Github.


  • No more conditional Safe (see #122).


  • Removed of equality constraints on Zoom and Magnify, as was done in lens earlier. This allows instances of Zoom and Magnify for FreeT. (Thanks to @treeowl.)

  • Fixed compilation on GHC 8.4.

  • Exported Focusing, etc. from Lens.Micro.Mtl.Internal.
  • Added &~.

  • Added <?= and <.=.

  • Added ?= and <~.

  • Added assign and modifying as synonyms for .= and %=.
  • Added <%=, <<%=, and <<.=.

  • Added forgotten copyright/authorship information.

  • Added preuse.

  • Bumped transformers version.
  • Bumped microlens version.

  • Added Lens.Micro.Mtl.Internal (which exports zooming type classes)

  • Added Safe Haskell pragmas.

  • Bumped microlens version.

  • Added preview (a synonym for (^?)).
  • Bumped microlens version.

  • Bumped microlens version.

  • Moved some internally used functions to Lens.Micro.Internal in microlens.
  • Bumped base version.

  • Package now compiles with -O2 and other optimisations by default.

  • Added zoom and magnify.

Initial release.