Am Mittwoch 21 Juni 2006 21:30 schrieb Brian Hulley:
Perhaps laziness is more "foundational", in that you can write
if2 c x y = if c then x else y
However:
1) What's the advantage of being able to define if2?
Well, you can easily define you own control structures (when, unless etc). This feature is wildly used in combinator libraries. Also, in a non-strict language recursive definitions are not limited to function types. Users of parser combinators heavily rely on this feature. Just try to define/use parsing combinators ins a strict language. The problem with eager evaluation is that it is too eager (expressions are sometimes evaluated too early) just as the problem with lazy evaluation is that it is too lazy (evaluations sometimes happen too late). Cheers, Ralf