[Haskell-cafe] Quickcheck examples and Data.Word32

[Sebastian Sylvan]

On 10/27/05, Joel Reymont <joelr1 at gmail.com> wrote:
> Would it cover the range between minBound :: Word32 and maxBound ::
> Word32? I cannot figure out how to do this since maxBound :: Int32 is
> less that that of Word32.
>
> Also, I get the following error with ghci -fglasgow-exts
>
> foo.hs:7:52: parse error on input `.'

Okay, try this then:

import Data.Word
import Test.QuickCheck

instance Arbitrary Word32 where
  arbitrary = do let mx,mn :: Integer
		     mx = fromIntegral (maxBound :: Word32)
	             mn = fromIntegral (minBound :: Word32)
		 c <- choose (mx, mn)
		 return (fromIntegral c)

That really should work. However the following will work too

instance Arbitrary Word32 where
  arbitrary = do c <- arbitrary :: Gen Integer
		      return (fromIntegral c)

Though I'm not sure of the range and distribution of the generated
Word32's (since it would depend on how fromIntegral behaves
transforming an Integer to a Word32 when the Integer is larger than
maxBound::Word32).


/S

> --
> module Foo where
>
> import Data.Word
> import Test.QuickCheck
>
> instance Arbitrary Word32 where
>      arbitrary = arbitrary :: Gen Integer >>= return . fromIntegral
>
> prop_Word32 :: Word32 -> Bool
> prop_Word32 a = a == a
>
>      Thanks, Joel
>
> On Oct 27, 2005, at 3:44 PM, Sebastian Sylvan wrote:
>
> > Something like (untested!):
> >
> > instance Arbitrary Word32 where
> >     arbitrary = arbitrary :: Gen Integer >>= return . fromIntegral
>
> --
> http://wagerlabs.com/
>
>
>
>
>
>


--
Sebastian Sylvan
+46(0)736-818655
UIN: 44640862