bracketOnError, while, forever

[Remi Turk]

On Mon, Mar 14, 2005 at 11:39:55AM -0000, Simon Marlow wrote:
> On 09 February 2005 12:00, Ross Paterson wrote:
> 
> > On Wed, Feb 09, 2005 at 11:50:48AM -0000, Simon Marlow wrote:
> >> On 08 February 2005 12:33, Thomas Jäger wrote:
> >> 
> >>> First of all
> >>>> -- Cale Gibbard
> >>>> comparing :: (Ord a) => (b -> a) -> b -> b -> Ordering
> >>>> comparing p x y = compare (p x) (p y)
> >>> fits nicely with the ...By functions from Data.List.
> >> 
> >>  sortBy (comparing fst)
> >> 
> >> is just too cute not to have.  Any objections?
> > 
> > only that it's not clear where to put it.
> 
> Just attempting to empty my inbox... we never resolved this one.  Perhaps there should be Data.Ord (and Data.Eq for that matter), and then we'd have an obvious place to put comparing?
> 
> Cheers,
> 	Simon

Some people (no idea how many, though at least 1 ;) seem to
prefer something like this:

cmp `on` conv = \x y -> conv x `cmp` conv y

sortBy (compare `on` fst)
groupBy ((==) `on` isSpace)

though some people (at least Henning Thielemann) prefer to call
it compose2.

http://www.haskell.org/hawiki/ThingsToAvoid
http://www.haskell.org/hawiki/ThingsToAvoid_2fDiscussion
contains some discussion about it.

Groeten,
Remi

-- 
Nobody can be exactly like me. Even I have trouble doing it.