[Haskell-cafe] Re: [Haskell] View patterns in GHC: Request for feedback

Jules Bean jules at jellybean.co.uk
Wed Jul 25 04:59:50 EDT 2007

apfelmus wrote:
> IMHO, the long-time debate about views is not whether they're useful (I
> think they are!) but which concrete form to choose. Unfortunately, all
> of the proposals so far are somehow like Dr. Jekyll and Mr. Hyde: one
> side is nice but the other is rather ugly.
> In the end, I might end up using the currently proposed pattern views,
> not because I'm fond of the proposal but simply because they're
> implemented and the pain of not using views is too big.

Maybe it would be helpful if Simon M would give a bit more flesh to the 
bones of his suggestion that all the examples in the proposal can be 
done more concisely without them.

apfelmus: Have you tried using pattern guards for views?

f s | y <: ys <- viewl s = ....
     | EmptyL  <- viewl s = ....

(did I get that right? :)

Personally I thought the basic proposal is quite nice, but the extra 
sugar for Maybes and tuples looked a bit ugly...


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