[Haskell-cafe] Looking for largest power of 2 <= Integer
sjanssen at cse.unl.edu
Wed Dec 5 17:23:42 EST 2007
On Tuesday 04 December 2007 15:47:19 David Benbennick wrote:
> On Dec 4, 2007 11:51 AM, Don Stewart <dons at galois.com> wrote:
> > Awesome. We can use this in Data.Bits, if you've got some QuickChecks
> > for it.
> Hear hear. But is there any way to just make the compiler use
> fastTestBit in place of testBit :: (Bits a) => a -> Int -> Bool when a
> = Integer? (That is, without having to introduce a new function to
> the public interface of Data.Bits.) Some kind of SPECIALIZE pragma,
> I've attached a program with two QuickCheck properties. Unfortunately
> they fail on negative Integers. I can't figure out why.
No fancy specialization is needed. Since testBit is part of the Bits class,
simply 'testBit = fastTestBit' in the instance for Integer.
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