[Haskell-cafe] Making new Unboxed Algebraic Types? (A Repa Problem)

[Hans Georg Schaathun]

On Mon, Jun 30, 2014 at 03:53:55PM -0400, Carter Schonwald wrote:
> boxity has nothing to do with parallelism. none :)

No, but it may affect /when/ haskell computes a value, and
if the computation is delayed until the value is requested,
then --hey-- we just missed the parallel opportunity.

Quite simply, Repa's computeP does not work as expected out of the
box when it is applied to a boxed return type.
If that amounts to «nothing to do with» in your book, that's ok;
it is still a problem which requires a solution.

BTW, I thought a bit more and the solution using NFData suggested in
http://stackoverflow.com/questions/16097418/parallel-repa-code-doesnt-create-sparks
was easier to implement than I feared, and more importantly, it 
works.  I don't find it entirely satisfactory though, so any hints on 
how to use unboxed arrays with composite constituent types are still 
very welcome.

-- 
:-- Hans Georg