[Haskell-cafe] Order of Evaluation

[Daniil Elovkov]

Hello

You may find this paper useful

http://research.microsoft.com/~simonpj/Papers/spineless-tagless-gmachine.ps.gz

It should give you the general feeling of how things are actually executed.

It's quite old, some things in GHC have changed, but the overall scheme, 
I believe, is the same. The competent people will correct me, if I'm wrong.



PR Stanley wrote:
> Hi
>  (take 4 . map (>0)) (f s t)
>  where
>     s = 2 : t
>     t = 3 : s
>  f = zipWith (-)
> What would be the order of evaluation for the above code? How would I 
> illustrate the evaluation step-by-step?
> I'm guessing that  the code necessitates lazy evaluation and as such it 
> starts with take then it applies f which in turn applies s and t and 
> zipWith until the first element satisfies the predicate in map and This 
> is repeated 4 times
> What does the list think?
> Many thanks,
> Paul
> P.S. I'm not done with induction. I'm just letting it rst for a bit.