Re: [Haskell-cafe] A question about "monad laws"

On Feb 11, 2008 10:18 PM, Uwe Hollerbach wrote:

If I fire up ghci, import Data.Ratio and GHC.Real, and then ask about the type of "infinity", it tells me Rational, which as far as I can tell is Ratio Integer...?

Yes, Rational is Ratio Integer. It might not be a good idea to import GHC.Real, since it doesn't seem to be documented at http://www.haskell.org/ghc/docs/latest/html/libraries/. If you just import Data.Ratio, and define

pinf :: Integer pinf = 1 % 0

ninf :: Integer ninf = (-1) % 0

Then things fail the way you expect (basically, Data.Ratio isn't written to support infinity). But it's really odd the way the infinity from GHC.Real works. Anyone have an explanation? -- I'm doing Science and I'm still alive.