Re: [Haskell-beginners] upgrade Hackage show to QuickCheck 2 for lambdabot

For some reason the generate function is not in QC2. Here's a quick fix: \begin{code} import Test.QuickCheck.Gen import System.Random generate :: Int -> StdGen -> Gen a -> a generate n rnd (MkGen m) = m rnd' size where (size, rnd') = randomR (0, n) rnd \end{code} Perhaps it would be better to ask the QC maintainers to re-include this function in the library... /Jonas On 3 July 2010 01:09, Antoine Latter wrote:

Including the café.

On Jul 2, 2010 8:49 AM, "Mark Wright" wrote:

Hi,

I'm trying to upgrade Hackage show to QuickCheck 2, after applying the diffs below (which may not be correct, since I am a beginner), I am left which this error message:

runghc ./Setup.hs build Preprocessing library show-0.3.4... Building show-0.3.4... [4 of 4] Compiling ShowQ            ( ShowQ.hs, dist/build/ShowQ.o )

ShowQ.hs:104:20: Not in scope: `generate'

Compilation exited abnormally with code 1 at Fri Jul  2 23:07:17

The error occurs in this method:

tests :: Gen Result -> StdGen -> Int -> Int -> [[String]] -> IO String tests gen rnd0 ntest nfail stamps  | ntest == 500  = done "OK, passed" ntest stamps  | nfail == 1000 = done "Arguments exhausted after" ntest stamps  | otherwise = case ok result of       Nothing    -> tests gen rnd1 ntest (nfail+1) stamps       Just True  -> tests gen rnd1 (ntest+1) nfail (stamp result:stamps)       Just False -> return $ "Falsifiable, after "                               ++ show ntest                               ++ " tests:\n"                               ++ reason result   where      result      = generate (((+ 3) . (`div` 2)) ntest) rnd2 gen      (rnd1,rnd2) = split rnd0

The QuickCheck 1 generate method is near the bottom this page:

http://hackage.haskell.org/packages/archive/QuickCheck/1.2.0.0/doc/html/Test...

but I can not find generate in QuickCheck 2.  I am wondering if you have any ideas on how to fix it?

I'm trying to package lambdabot on Solaris.  I have already packaged the Haskell Platform and about 90 packages, they are in:

http://pkgbuild.sourceforge.net/spec-files-extra/

Thanks very much, Mark

here are the diffs:

goanna% diff -wc show-0.3.4-orig/ShowQ.hs show-0.3.4/ShowQ.hs *** show-0.3.4-orig/ShowQ.hs    Wed Jan 20 11:24:11 2010 --- show-0.3.4/ShowQ.hs Fri Jul  2 23:07:13 2010 *************** *** 12,22 **** --- 12,25 ----

 import qualified Test.SmallCheck (smallCheck, Testable)  import Test.QuickCheck + import Test.QuickCheck.Arbitrary  import Data.Char  import Data.List  import Data.Word  import Data.Int  import System.Random + import Control.Exception (evaluate) + import Test.QuickCheck.Property (ok, stamp)

 type T = [Int]  type I = Int *************** *** 23,36 **** --- 26,45 ----

 instance Arbitrary Char where      arbitrary     = choose (minBound, maxBound) + + instance CoArbitrary Char where      coarbitrary c = variant (ord c `rem` 4)

 instance Arbitrary Word8 where      arbitrary = choose (minBound, maxBound) + + instance CoArbitrary Word8 where      coarbitrary c = variant (fromIntegral ((fromIntegral c) `rem` 4))

 instance Arbitrary Ordering where      arbitrary     = elements [LT,EQ,GT] + + instance CoArbitrary Ordering where      coarbitrary LT = variant 1      coarbitrary EQ = variant 2      coarbitrary GT = variant 0 *************** *** 37,42 **** --- 46,53 ----

 instance Arbitrary Int64 where    arbitrary     = sized $ \n -> choose (-fromIntegral n,fromIntegral n) + + instance CoArbitrary Int64 where    coarbitrary n = variant (fromIntegral (if n >= 0 then 2*n else 2*(-n) + 1))

 instance (Integral a, Arbitrary a) => Arbitrary (Ratio a) where *************** *** 48,53 **** --- 59,65 ----                              else (b % a)                           else (a % b)

+ instance (Integral a, CoArbitrary a) => CoArbitrary (Ratio a) where    coarbitrary m = variant (fromIntegral $ if n >= 0 then 2*n else 2*(-n) + 1)      where n = numerator m

*************** *** 87,93 ****         Just False -> return $ "Falsifiable, after "                                 ++ show ntest                                 ++ " tests:\n" !                                ++ unlines (arguments result)     where        result      = generate (((+ 3) . (`div` 2)) ntest) rnd2 gen        (rnd1,rnd2) = split rnd0 --- 99,105 ----         Just False -> return $ "Falsifiable, after "                                 ++ show ntest                                 ++ " tests:\n" !                                ++ reason result     where        result      = generate (((+ 3) . (`div` 2)) ntest) rnd2 gen        (rnd1,rnd2) = split rnd0 goanna%

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