[Haskell-cafe] multiple computations, same input

[Greg Fitzgerald]

>
> ...Anyway, I can't help but think that there might be a happy medium
> between eager and lazy evaluation.


What I'd love to see is the compiler continue to be call-by-need, but be
smart enough to recognize when multiple expressions will all eventually need
to be evaluated.  A simple example:

    show (a + b)

(+) requires *both* 'a' and 'b' be evaluated to show the result, not 'a'
*then* 'b'.  It'd be great if the compiler can seek out any shared lazy data
structures in evaluating 'a' and 'b', and start computing them both with one
element at a time.

Has anyone put any thought into something like this?

Thanks,
Greg
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