SmallCheck properties for lens

Latest on Hackage:0.3

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BSD3 licensed by Danny Navarro
Maintained by

Lens SmallCheck

Hackage Version Build Status

smallcheck properties inspired by lens-properties. They can be used to validate the laws for:

  • Lens
  • Setter
  • Traversal
  • Iso
  • Prism

Use this package to create your own fine tuned tests. For preassembled test runners with minimal setup and sensible defaults, you can use tasty-lens.


Contributions and bug reports are welcome!

Please feel free to contact jdnavarro on the #haskell IRC channel on


Change Log

All notable changes to this project will be documented in this file. This file follows the formatting recommendations from Keep a CHANGELOG. This project adheres to Semantic Versioning.

0.3 - 2015-09-11 ### Changed - More sensible function names assuming qualified imports. - Pass functor to use in Traversal as a Proxy instead of hardcoding the functors. - Rank-2 Lens-Like everywhere.


  • Exhaustive property testing using Series product. Previous properties renamed appending Sum.


  • Main re-export module.
  • Move Tasty modules to a separate package tasty-lens.
  • pureMaybe. Now a Proxy functor is used.

0.1 - 2015-05-27


  • SmallCheck properties for each lens laws.
  • tasty test trees for each Lens type.
  • Tests for some Lens.
Used by 1 package:
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