On 7/6/07, Thomas Hartman <[EMAIL PROTECTED]> wrote:
I am a total quickcheck noob. Is there a way to find out what predicate test "<function>" is, below?
The trick that I know of to do that is to not generate a function in the first place, but a data type which can represent various functions of this type. Whenever we want to use the data type as a function in the test we convert it to a function. Let's take an example: data IntFun = Plus5 | Mult5 deriving show apply :: IntFun -> Int -> Int apply Plus = (+ 5) apply Mult = (* 5) instance Arbitrary IntFun where arbitrary = elements [Plus,Mult] prop_foo f a = apply f a == a Ofcourse the data type will typically be much more complicated depending on what kind of functions you want to be able to generate. This trick is documented in the following paper: http://www.st.cs.ru.nl/papers/2006/koop2006-TestingOfHigherOrderFunctionsAPLAS.pdf HTH, Josef _______________________________________________ Haskell-Cafe mailing list [email protected] http://www.haskell.org/mailman/listinfo/haskell-cafe
