Functional Programming: A PragPub Anthology

A Brief Introduction to QuickCheck

QuickCheck was originally written in 2000 by Koen Claessen and John Hughes. Their paper on the subject^[28] is a detailed introduction. We won’t go into a lot of detail in this chapter, but reading this paper is highly encouraged. To get better acquainted, let’s write a simple property. We’ll use an example directly from the Haskell wiki.^[29]

quickCheck ((\s -> s == s) :: [Char] -> Bool)

We can try it by firing up GHCi.

$ stack exec ghci
GHCi, version 7.10.3: http://www.haskell.org/ghc/  :? for help
Prelude> import Test.QuickCheck
Prelude Test.QuickCheck> quickCheck ((\s -> s == s) :: [Char] -> Bool)
+++ OK, passed 100 tests.

First, we import the QuickCheck module. You may have noticed that we did that ...