[Haskell-beginners] ($) operator
schwidom at gmx.net
Sun Jan 25 09:25:03 EST 2009
On Sat, Jan 24, 2009 at 07:37:29PM +0000, John Hartnup wrote:
> I'm working through Real World Haskell, and although it's going well
> (I just finished the exercise to write a glob matcher without using a
> regex library, and I'm pleased as punch), I keep seeing the ($)
> operator, and I'm not sure I understand its use. If the book explains
> it, I've been unable to find it.
> Empirically, it seems like:
> a $ b c d e f
> .. is equivalent to ..
> a (b c d e f)
> But is that it's only purpose? To placate the LISP haters by removing
> (1 +) 2 does the same thing as (1 +) $ 2, and has the same type.
> Am I missing something?
I made some Examples for better understanding:
-- creating an $ like function:
f g x = (g x)
-- some tests comparing $ with f:
5 == ($ 2) (+ 3)
5 == (`f` 2) (+ 3)
5 == (\x -> (($) x 2)) (+ 3)
5 == (\x -> (f x 2)) (+ 3)
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