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Re: [Scheme-reports] DELAY AND FORCE
9 minutes ago, Ray Dillinger wrote:
> What I could and did implement without running into problems was
> lazy and eager functions as opposed to delayed and forced versus
> eager evaluations. But the semantics of mixing calls to lazy and
> eager functions can be confusing, especially when the functions are
> evaluated in the course of expanding macros.
... Which leads to another bad point in R5RS that R7RS retains: saying
that the language might treat a promise as equivalent to its forced
value. That kind of behavior is not only difficult to do and
confusing as a result, it also leads to a very different language
which "suffers" from some of the things that lazy languages do. (For
example a "value" can now actually be a computation). Leaving it as a
possible option in a standard is IMO reckless.
((lambda (x) (x x)) (lambda (x) (x x))) Eli Barzilay:
http://barzilay.org/ Maze is Life!
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