Re: [xsl] XSLT repetition constructs

["Dimitre Novatchev dnovatchev@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

> > I have to confess I always find it difficult to come up with a convincing
> > use case for fold-right().
>
> Symmetricality and karma?

I haven't been engaged with this for some time, but from what I
remember, foldl() is executed eagerly and can lead to call-stack
overflow, while foldr() allows lazy evaluation and thus doesn't lead
to stack overflow. This is why in FP (Haskell) using foldr() is
generally preferred to using foldl()

Also, if the chain of execution leads to result that would allow
short-cutting -- as in getting a 0 when computing the product of a
list of numbers, foldl() will still continue to do the multiplications
until the whole list is processed, while foldr() produces the result
immediately.

Must dig for some specific material that discusses this at length.

Cheers,
Dimitre


On Thu, Mar 7, 2019 at 5:23 AM Peter Flynn peter@xxxxxxxxxxx
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> On 7 March 2019 11:56:10 "Michael Kay mike@xxxxxxxxxxxx"
> <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> > I have to confess I always find it difficult to come up with a convincing
> > use case for fold-right().
>
> Symmetricality and karma?
>
> P
>
> 



-- 
Cheers,
Dimitre Novatchev
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