Hello Haskell Café,

A new version of LeanCheck is out (v1.0.0).  LeanCheck is a property testing library (like QuickCheck) that tests values enumeratively.

Example.  Here is a simple example of LeanCheck in action showing that sorting is idempotent and list union is not commutative:

> import Test.LeanCheck
> import Data.List (sort, union)

> check $ \xs -> sort (sort xs) == sort (xs::[Int])
+++ OK, passed 200 tests.

> check $ \xs ys -> xs `union` ys == ys `union` (xs::[Int])
*** Failed! Falsifiable (after 4 tests):
[] [0,0]

LeanCheck works on all types that are instances of the Listable typeclass and is able to derive instances automatically using either Template Haskell or GHC.Generics. See LeanCheck’s Haddock documentation for more details.  LeanCheck is compatible with Hspec, Tasty and test-framework.

What's new?  Version 1.0.0 signalizes stability in the API.  LeanCheck has not actually changed much in the past couple of years and there are no significant differences between the early 0.9 series.

Installing.  You can find LeanCheck on Hackage or GitHub.  It is also tracked on Stackage.  You can install it with:

$ cabal install leancheck

– Rudy