On Fri, 3 Feb 2006 19:33:12 -0000
"Brian Hulley"
I've been thinking along these lines too, because it has always seemed to me that laziness is just a real nuisance because it hides a lot of inefficiency under the carpet as well as making the time/space behaviour of programs difficult to understand...
One question is how to get some kind of "do" notation that would work well in a strict setting. The existing "do" notation makes use of lazyness in so far as the second arg of >> is only evaluated when needed. Perhaps a new keyword such as "go" could be used to use >>= instead ie:
go {e1;e2;e3} === e1 >>= (\_-> (e2 >>= (\_->e3)))
That's not necessary. >> has something in common with if', where if' True x _ = x if' False _ y = y - in both cases, it makes sense to evaluate the arguments lazily. So simply make strictness the default and have laziness annotations (for arguments), instead of making laziness the default and having strictness annotations.
A related question is: could monadic programming ever be as efficient as side-effect programming?
Monads can be viewed as code generators. So, with partial evaluation, my guess is yes, at least in many important cases. -- Robin