[Haskell-cafe] Re: Math questions

[Mujtaba Boori]

*Pete Chown and Dan Doel. Thank you for your solution. I actually It was not
homework . It was just a a past exam question trying to answer . *
**but your solution is very long , so I don't think he wants answer this
long in the exams. I think this answer agree100 f g = map f xs == map g xs
where xs = [1..100] from  Richard O'Keefe
is do the job.

**Anyway , your solution help understand more about Haskell not only this
question . Many thanks to you guys.

On 27 May 2010 02:04, Dan Doel <dan.doel at gmail.com> wrote:

> On Wednesday 26 May 2010 5:38:57 pm Pete Chown wrote:
> > test :: (Eq a) => (Int -> a) -> (Int -> a) -> Bool
> > test f1 f2 = unsafePerformIO $ do
> >      goodSoFar <- newIORef True
> >      forLoop 1 100 $ \i ->
> >        when (f1 i /= f2 i) $ writeIORef goodSoFar False
> >      readIORef goodSoFar
>
> The problem with this algorithm is that it needlessly tests f1 against f2
> for
> all i, even when a non-matching value has has already been found. Using the
> power of call-with-current-continuation, I have constructed an algorithm
> that
> lacks this deficiency:
>
>    import Control.Monad.Cont
>
>    test f g = flip runCont id . callCC $ \escape ->
>      do forM_ [1..100] $ \n ->
>           when (f n /= g n) $
>             escape False
>         return True
>
> This should perform almost 75% less work in the testFunc1 case! It
> certainly
> feels much snappier.
>
> -- Dan
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-- 
Mujtaba Ali Alboori
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