Another experiment may be revealing: :t 3 2
On Fri, Nov 16, 2012 at 7:46 AM, Daryoush Mehrtash <dmehrt...@gmail.com>wrote: > I see the point with :t (.) that > > max.(+1) 2 2 > > is the same as > > max. 3 2 > > Which is not what I want. > > But I have no idea what the type signature of this expression mean now > > Prelude> :t max. 3 2 > max. 3 2 :: (Ord b, Num a1, Num (a1 -> a -> b)) => a -> b -> b > > Any idea? > > Daryoush > > > On Thu, Nov 15, 2012 at 11:19 PM, Ramana Kumar > <ramana.ku...@cl.cam.ac.uk>wrote: > >> Hi Daryoush, >> >> I recommend you try these experiments first, and then reply back if >> you're still confused. >> >> :t max >> >> :t (+1) >> >> :t max . (+1) >> >> :t (+1) 2 >> >> :t (.) >> >> >> On Fri, Nov 16, 2012 at 7:10 AM, Daryoush Mehrtash >> <dmehrt...@gmail.com>wrote: >> >>> I am having hard time understanding how removing the >>> outer parenthesis in >>> >>> (max.(+1)) 2 2 >>> >>> to >>> >>> max.(+1) 2 2 >>> >>> changes the meaning of expression. >>> >>> My expectation was that "max.(+1) takes two numbers and returns the max >>> as defined in the type: >>> >>> :t max.(+1) >>> max.(+1) :: (Ord b, Num b) => b -> b -> b >>> >>> >>> >>> With parenthesis it does what I expect it to: >>> >>> >>> Prelude> :t (max.(+1)) 2 2 >>> (max.(+1)) 2 2 :: (Ord b, Num b) => b >>> Prelude> (max.(+1)) 2 2 >>> 3 >>> >>> >>> But if I remove the parenthesis I get a beast that I have no idea what >>> its type signature mean any more >>> >>> Prelude> :t (max.(+1)) 2 2 >>> (max.(+1)) 2 2 :: (Ord b, Num b) => b >>> Prelude> :t max.(+1) 2 2 >>> max.(+1) 2 2 :: (Ord b, Num a1, Num (a1 -> a -> b)) => a -> b -> b >>> >>> >>> How did removal of parenthesis changed the meaning? How do you >>> interpret the type: "(Ord b, Num a1, Num (a1 -> a -> b)) => a -> b -> b"? >>> >>> Thanks >>> >>> >>> >>> -- >>> Daryoush >>> >>> Weblog: http://onfp.blogspot.com/ >>> >>> _______________________________________________ >>> Haskell-Cafe mailing list >>> Haskell-Cafe@haskell.org >>> http://www.haskell.org/mailman/listinfo/haskell-cafe >>> >>> >> > > > -- > Daryoush > > Weblog: http://onfp.blogspot.com/ >
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