22 Jul
2010
22 Jul
'10
7:01 p.m.
An alternative to the `asTypeOf` idiom, which is also Haskell 98, is to use a newtype instead of a dummy argument: newtype RangeSize i = RangeSize { getRangeSize :: Int } boundedRangeSize :: Ix i => (i,i) -> RangeSize i boundedRangeSize = RangeSize . rangeSize bdRangeSize :: (Ix i, Bounded i) => RangeSize i bdRangeSize = boundedRangeSize (minBound, maxBound) Now you can call ghci> getRangeSize (bdRangeSize :: RangeSize Bool) 2 without language extensions and avoid the extra applications due to the dummy argument and the `asTypeOf` call. Sebastian -- Underestimating the novelty of the future is a time-honored tradition. (D.G.)