[Haskell-beginners] types, parentheses, application, composition

[Christopher Howard]

Could someone explain more precisely to me what is the significance of
parentheses in the type of an expression? Are they just some kind of
syntactic sugar, that simplifies into a type without them, or are they
more like parentheses in algebra, or...?

In particular, I'm having difficulty understanding the results of
composition or application that involves parentheses... I think I've got
it figured out and then I find another strange expression that doesn't
have the type I expect. Here is an example using the (self-made)
function "sqr":

code:
--------
> :t sqr
sqr :: Double -> Double
> :t (.)
(.) :: (b -> c) -> (a -> b) -> a -> c
> :t (. sqr)
(. sqr) :: (Double -> c) -> Double -> c
> :t ((. sqr) .)
((. sqr) .) :: (a -> Double -> c) -> a -> Double -> c
--------

Everything makes sense up until the last expression, "((. sqr) .)".
Where did the "(a -> Double -> c)" come from? What's going on here?

-- 
frigidcode.com

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