lazy thoughts

[Fawzi Mohamed]

On 2009-01-13 10:27:10 +0100, Robert Fraser <fraserofthenight at gmail.com> said:

> Andrei Alexandrescu wrote:
>> Robert Fraser wrote:
>>> Andrei Alexandrescu wrote:
>>>> Dunno. According to SPJ, automatically parallelizing map was a failed 
>>>> experiment in Haskell. Explicit parallelizing a la pmap seems to be the 
>>>> way to go.
>>> 
>>> Source? I think as processors grow in number, automatic paralellization 
>>> will become increasingly important, so I'm wondering why it was a 
>>> "failed experiment"?
>> 
>> Private conversation.
>> 
>> Andrei
> 
> Did he mention what the implementation was like and/or what the problem 
> was (i.e. too much overhead, etc.)?

Probably something of the following:
1) In general when you do map you cannot exclude that the user expects 
sequentiality, or at least not parallelism.

2) if you use forward iterators (and lazy lists are such) are *very* 
sequential.

By the way now that you are going more in the lazy direction you might 
want to consider again the problem with pure function not accepting 
lazy structures (invariant structures have to be fully evaluated).
I had brought this up quite some time ago...

Fawzi