[Haskell-cafe] Newbie: State monad example questions

Olivier Boudry olivier.boudry at gmail.com
Fri May 23 21:37:32 EDT 2008


On Fri, May 23, 2008 at 5:17 PM, Thomas Hartman <tphyahoo at gmail.com> wrote:

> > Maybe I don't like to read backwards. ;-)
>
> >>> (from Control.arrow) is like flip (.)
>
>
That's something I considered. I like the `|>` operator found in F# (I hope
it's not a curse word on this list) which is equivalent to `flip (.)`.

It's easy to define in Haskell

(|>) :: (a -> b) -> (b -> c) -> a -> c
(|>) = flip (.)

I even started to use it in my code and then stopped. It may be a stupid
concern but as many optimizations performed by GHC are made through rewrite
rules and I was worried that those rules may not fire when using this new
operator.

I never thought of using `>>>` for this, but again I wonder how it will work
with rewrite rules.

Olivier.
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