Package Info

ghc-microlens


A tiny lens library with no dependencies


Unspecified

NOTE: If you're writing an app, you probably want <http://hackage.haskell.org/package/microlens-platform microlens-platform> – it has the most features. <http://hackage.haskell.org/package/microlens microlens> is intended more for library writers who want a tiny lens library (after all, lenses are pretty useful for everything, not just for updating records!).

This library is an extract from <http://hackage.haskell.org/package/lens lens> (with no dependencies). It's not a toy lenses library, unsuitable for “real world”, but merely a small one. It is compatible with lens, and should have same performance. It also has better documentation.

There's a longer readme <https://github.com/monadfix/microlens#readme on Github>. It has a migration guide for lens users, a description of other packages in the family, a discussion of other lens libraries you could use instead, and so on.

Here are some usecases for this library:

  • You want to define lenses or traversals in your own library, but don't want

to depend on lens. Having lenses available often make working with a library more pleasant.

  • You just want to be able to use lenses to transform data (or even just use

'over _1' to change the first element of a tuple).

  • You are new to lenses and want a small library to play with.

However, don't use this library if:

  • You need 'Iso's, 'Prism's, indexed traversals, or actually anything else

which isn't defined here (though some indexed functions are available elsewhere – containers and vector provide them for their types, and <http://hackage.haskell.org/package/ilist ilist> provides indexed functions for lists).

  • You want a library with a clean, understandable implementation (in which case

you're looking for <http://hackage.haskell.org/package/lens-simple lens-simple>).

As already mentioned, if you're writing an application which uses lenses more extensively, look at <http://hackage.haskell.org/package/microlens-platform microlens-platform> – it combines features of most other microlens packages (<http://hackage.haskell.org/package/microlens-mtl microlens-mtl>, <http://hackage.haskell.org/package/microlens-th microlens-th>, <http://hackage.haskell.org/package/microlens-ghc microlens-ghc>).

If you want to export getters or folds and don't mind the <http://hackage.haskell.org/package/contravariant contravariant> dependency, please consider using <http://hackage.haskell.org/package/microlens-contra microlens-contra>.

If you haven't ever used lenses before, read <http://hackage.haskell.org/package/lens-tutorial/docs/Control-Lens-Tutorial.html this tutorial>. (It's for lens, but it applies to microlens just as well.)

Note that microlens has no dependencies starting from GHC 7.10 (base-4.8). Prior to that, it depends on transformers-0.2 or above.


License: BSD-3-Clause
URL: https://hackage.haskell.org/package/microlens

Categories

Releases

Package Version Update ID Released Package Hub Version Platforms Subpackages
0.4.12.0-bp155.2.16 info GA Release 2023-05-22 15 SP5
  • AArch64
  • ppc64le
  • s390x
  • x86-64
  • ghc-microlens
  • ghc-microlens-devel
0.4.12.0-bp154.1.12 info GA Release 2022-05-09 15 SP4
  • AArch64
  • ppc64le
  • x86-64
  • ghc-microlens
  • ghc-microlens-devel
0.4.11.2-bp153.1.20 info GA Release 2021-04-08 15 SP3
  • AArch64
  • ppc64le
  • x86-64
  • ghc-microlens
  • ghc-microlens-devel
0.4.11.2-bp152.1.16 info GA Release 2020-06-16 15 SP2
  • AArch64
  • ppc64le
  • x86-64
  • ghc-microlens
  • ghc-microlens-devel
0.4.10-bp151.2.2 info GA Release 2019-07-17 15 SP1
  • ppc64le
  • s390x
  • x86-64
  • ghc-microlens
  • ghc-microlens-devel
0.4.10-bp151.1.12 info GA Release 2019-05-31 15 SP1
  • AArch64
  • ghc-microlens
  • ghc-microlens-devel
0.4.8.0-bp150.2.4 info GA Release 2018-07-30 15
  • AArch64
  • ppc64le
  • x86-64
  • ghc-microlens
  • ghc-microlens-devel
0.4.5.0-2.9 info 5585 2016-09-14 12 GA-SP5
  • AArch64
  • s390x
  • x86-64
  • ghc-microlens
  • ghc-microlens-devel
0.4.5.0-2.3 info 5585 2016-09-14 12 GA-SP5
  • ppc64le
  • ghc-microlens
  • ghc-microlens-devel