> streams :: (Int -> Bool, Int -> Bool) -> (Int,Int) ->
>[(Maybe Int,Maybe Int)]
> streams (p,q) (x,y)
>
> | p x && p y = (Just x , Just y ) : xs
> | p x= (Just x , Nothing) : xs
> | p y= (Nothing, Just y ) : xs
> | otherwise = xs
>
> where xs = str
> I think you have a choice between risking a space leak and repeating
> evaluation.
Well, sometimes neither is a good option...
> If you use 'streams' like this
>
> let (xs, ys) = streams ...
> in -- anything which requires the first element of xs while ys may
> -- still be us
Hrm. This is interesting. So one option you already considered would be
to put the writing inside 'streams', which probably should be
disprefered. Have you considered doing something like:
streams :: (Int -> Bool, Int -> Bool) -> (Int,Int) ->
[(Maybe Int,Maybe Int)]
streams (p,q) (x,
Jorge Adriano writes:
:
| streams :: (Int->Bool, Int->Bool)->(Int, Int)->([Int],[Int])
| streams (p,q) (x,y) = (xs',ys')
| where
| (xs,ys) = streams (p,q) ((x+y),(y-x))
| xs' = if p x then x:xs else xs
| ys' = if q y then y:xs else ys
|
|
| - produces a pair of ('infinit
I might have been not very clear in my last mail. I decided to post again, and
go straight to the point, with some small examples.
Consider the following function streams.
streams :: (Int->Bool, Int->Bool)->(Int, Int)->([Int],[Int])
streams (p,q) (x,y) = (xs',ys')
where
(xs,ys) = streams
There is also a job here:
http://www.edaptive.com/career/index.htm
It isn't exactly functional programming or Haskell, but it is related (more
so than it looks from the job description). Please do consider it, if it
sounds interesting to you.
Dave Barton
EDAptive Computing
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