[Haskell-cafe] Automatic parallelism in Haskell, similar to "make -j4"?

[Ketil Malde]

Bulat Ziganshin <bulat.ziganshin at gmail.com> writes:

> Hello T,
>
> Monday, November 3, 2008, 2:28:08 AM, you wrote:
>
>> What would it take to implement a -j equivalent for, say, GHC?  Or if
>> this is not possible, what is wrong with my reasoning?
>
> problem is that make have rather large pices of work which it can run
> parallel. if ghc will try to parallel every machine operation, it will
> pend more time maintaining these jobs. 'par' is just the way to tell
> GHC "this part of job is large enough"

..and also that this piece of work will actually need to be evaluated.  With
lazyness, a program can have subexpressions that are bottom as long as they are
not evaluated, any kind of speculative execution must take care to handle this
properly. 

-k
-- 
If I haven't seen further, it is by standing in the footprints of giants