Re: PROPOSAL: Restrict the type of (^), (^^), and add genericPower, genericPower'

On 17/11/2007, Ian Lynagh wrote:

On Sat, Nov 17, 2007 at 11:45:52AM -0500, Cale Gibbard wrote:

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On 17/11/2007, Ian Lynagh wrote:

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(^) :: (Num a) => a -> Int -> a genericPower :: (Num a, Integral b) => a -> b -> a

This is a move in the opposite direction from what I'd really like to see. The Int type is usually a premature optimisation, and I usually prefer to work with Integer as much as possible, but this just means more fromIntegral conversions (or the use of the awkwardly named general version).

I would much prefer for length, !!, etc. to have more general types, not less general (with compiler specialisation on Int of course).

This proposal is about making (^) and (^^) consistent with everything else. Making everything use Integer rather than Int is an orthogonal question.

Someone could also make a Prelude.Integer module, that exports foo :: ... Integer ... foo = genericFoo for various foo which are specialised to Int in Prelude, and reexports all other functions from Prelude. Getting rid of implicit Prelude imports would help too.

Thanks Ian

I don't want the types specialised to Integer either though. I'd want to have the types be as generic as possible, but include appropriate pragmas to tell GHC how to optimise when they're applied monomorphically.