Re: [Haskell-cafe] Re: Re-order type (flip map)

No, wrong. I am speaking nonsense here. Of course one also needs to define a *forward* function composition operator to get the effect you originally wanted. My point was: you need to find/define two operators, not just one. That still holds :) Best, On 10 October 2010 23:47, Ozgur Akgun wrote:

On 10 October 2010 22:32, Johannes Waldmann wrote:

...

Oh, and while we're at it - are there standard notations for "forward" function composition and application?

I mean instead of h . g . f $ x I'd sometimes prefer x ? f ? g ? h but what are the "?"

While asking you use the same symbol for function composition, and something like inverse function application. I don't think there exists an operator ?, such that h . g . f $ x is equivalent to x ? f ? g ? h.

But you can simply define an inverse function application like the following and have a close enough alternative,

($$) :: a -> (a -> b) -> b ($$) = flip ($) infixl 5 $$

Now the following two expression are identical, I suppose:

h . g . f $ x x $$ f . g . h

Cheers, Ozgur

-- Ozgur Akgun