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
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