Hello, What if the '2' that appears in splitPos is itself generated (ie. an int parameter of splitFunGen) and you replace `div` by `mod`? Sorry, I have no code to show right now. HTH Arnaud On Thu, Jun 23, 2011 at 10:58 AM, jean-christophe mincke < jeanchristophe.mincke@gmail.com> wrote:

Hello Café,

I am using quicheck for some kind of non trivial tests.

The general form of these tesst is summarized by the following code.

-- Function to be tested. Given a list of splitting functions, split the given list process :: [a] -> [[a] -> [a]] -> [a] process l splitFuns = List.foldl proc l splitFuns where proc l splitFun = splitFun l

-- a split function generator splitFunGen :: Gen ([a] -> [a]) splitFunGen = return $ proc where proc l = let splitPos = List.length l `div` 2 -- Problem I would like splitPos = some random value between [0 and length of l] in fst $ List.splitAt splitPos l

splitFunsGen :: Gen [[a] -> [a]] splitFunsGen = vectorOf 20 splitFunGen

instance Show a => Show ([a] -> [a]) where show _ = " a split fun "

r = quickCheck $ forAll splitFunsGen prop where prop splitFuns = let l = process [1..100] splitFuns in List.length l >= 0 -- dummy test here for the sake of example

The process to be tested takes a list that is randomly perturbated (spitFuns). The result of each perturbation is fed into the next perturbation.

Ideally I would like the perturbating function to depend on the previous perturbated list (see computation of splitPos in splitFunGen).

I am not sure how I could use quickcheck in this case.

Has anyone a better idea?

Thanks

J-C

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