Question About lists

[Shlomi Fish]

On Wed, 1 Jan 2003, Andrew J Bromage wrote:

> G'day all.
>
> On Mon, Dec 30, 2002 at 01:47:37PM -0600, Artie Gold wrote:
>
> > One suggestion, though is that you're working too hard; there's really
> > no reason to define a locally defined function. The much simpler:
> >
> > long [] = 0
> > long (x:xs) = 1 + long xs
> >
> > will do quite nicely.
>
> It has quite different performance characteristics, though.  In
> particular, this uses O(n) stack space whereas the accumulator one
> uses O(1) stack space.
>

This is assuming Haskell is properly tail-recursive. However, as far as I
was told due to the lazy evaluation that is not the case for such
functions.

Regards,

	Shlomi Fish

> Cheers,
> Andrew Bromage
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> http://www.haskell.org/mailman/listinfo/haskell
>



----------------------------------------------------------------------
Shlomi Fish        shlomif@vipe.technion.ac.il
Home Page:         http://t2.technion.ac.il/~shlomif/

He who re-invents the wheel, understands much better how a wheel works.