[Haskell-cafe] derivation of mapP, a parallel, lazy map

[Roberto Zunino]

Felipe Lessa wrote:
> Have you seen parBuffer? I'd also recommend looking at its source.

I wonder if it would be possible to make a variant of parBuffer so that 
the following evaluates to 1:

 > take 1 $ parBuffer 10 r0 (1:2:3:undefined)
*** Exception: Prelude.undefined

Maybe we should use a more complex intermediate structure as

    data ExcList a = Nil | Cons a (ExcList a) | Deferred Exception

and catch the exception through some unsafe stuff? Would that be a good 
idea?

Zun.