Re: [Haskell-cafe] Hspec + QuickCheck passing type

I would recommend using http://hackage.haskell.org/package/base-4.8.2.0/docs/Prelude.html#v:asTypeOf And passing a dummy variable of the correct type. -Will

On Mar 28, 2016, at 12:53, Martijn Rijkeboer wrote:

Hi,

I'm writing the following Hspec + QuickCheck test for some type:

context "Type1" $ it "decode inverses encode" $ property $ \x -> (decode . encode) x == Right (x::Type1)

However, I have a number of these types, and I could write the same test for every type, but that isn't very DRY. Therefore I would like to put the test in a function and call that function for every type. Something like the following:

typeTest name = do context name $ it "decode inverses encode" $ property $ \x -> (decode . encode) x == Right x

Unfortunately this doesn't work, since QuickCheck doesn't know which Arbitrary instance to use. How can I pass the type, e.g. x::Type1, to this function so QuickCheck knows what Arbitrary instance to use?

Kind regards,

Martijn Rijkeboer

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