Re: Proposal: Add hasBitSize to Data.Bits.Bits

On Sat, Jul 28, 2012 at 5:33 PM, Antoine Latter wrote:

On Sat, Jul 28, 2012 at 11:57 AM, Andreas Abel wrote:

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On 28.07.12 4:40 PM, John Lato wrote:

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From: Edward Kmett

On Fri, Jul 27, 2012 at 3:42 PM, Ian Lynagh wrote:

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On Fri, Jul 27, 2012 at 03:06:04PM -0400, Edward Kmett wrote:

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There is currently no way to know whether or not calling Data.Bits.bitSizewill crash your program.

I propose extending the Bits class to include:

hasBitSize :: Bits b => b -> Bool

I'm in favor of changing the type of bitSize, although since none of my code uses that function it's an easy position for me to take.

+1. The Haskellish solution would let return bitSize a Maybe.

Is 'bitSize' a useful function to use monomorphically? It seems a waste and irritating to have it return Maybe if I'm not using Integer.

That is a great point. Most my uses of 'bitSize' are monomorphic and Maybe would just be silly. OTOH, I'd be more than happy to fix up any polymorphic code to include a new BitSize constraint. Thomas