Jed Brown wrote:
The idea with QC is that you start with `simple' random input and progress to more `complicated' input. If say, you are testing a function that builds a list with length equal to the output of the QC-generated function (Double->Int) (with positive precondition) you could be building a huge list very early. This wouldn't happen with other types since `simple' QC-generated functions for, say, (Int->Int) will map small integers to small integers.
I don't think this has anything to do with the definition of coarbitrary. As I understand things: coarbitrary is a function of type x -> StdGen arbitrary is a function of type StdGen -> Int -> x For the type "x -> y", arbitrary is equal to \g n -> (\x -> let g' = coarbitrary x in arbitrary g' n) I did an experiment in QC1 (with patch). Here are two properties: prop_f (f :: Double -> Int) x = trace (show $ f x) True prop_g (f :: Int -> Int) x = trace (show $ f x) True Below is the output. Do you think that one is "more simple" than the other? Patrick 1 0 2 -2 0 0 0 0 2 -3 00 11 -3 -5 -9 05 06 17 -5 49 30 -1 -1 33 -8 -4 66 27 78 09 60 01 -8 83 -12 35 -4 13 38 -1 -4 -1 02 -10 -3 45 06 -10 -12 -4 20 -7 -18 -2 84 -10 -2 13 38 29 60 -6 12 20 -12 95 -8 -22 58 49 90 -12 12 -12 -1 -1 -14 -14 27 -1 00 01 -16 23 54 25 24 -15 48 14 -10 -37 02 -19 84 17 -15 -19 -1 42 -3 1 -3 1 3 -3 -4 -4 -2 -3 10 -1 02 43 14 05 -1 07 18 -1 -3 21 -4 -5 34 25 -1 17 18 -8 -4 31 13 53 64 95 06 27 -2 -6 60 10 72 -2 -3 45 36 -9 16 39 -4 01 27 -3 -22 -7 -4 -14 -1 -6 -8 -1 -23 -13 14 45 -24 17 -1 49 -5 25 -13 11 44 05 26 12 -12 -33 00 11 27 93 35 25 -3 -6 98 -12 -20 10 -11 43 34 12 -43 17 -3 09