On Apr 5, Matthias Felleisen wrote:
>
> 1. Is this going into the code base?
Already did, I'll send a message shortly.
> 2. Why is for on lazy things not practical?
There are two kinds of laziness that you can talk about:
* Iterating over a lazy sequence like an infinite list.
(for ([x (in-lazy-list (letrec ([l (lazy-append '(1 2 3) l)])
l))])
...)
* Having the sequence value itself be lazy.
(for ([x (letrec ([seq (lazy-sequence-append (in-list '(1 2 3))
seq)])
seq)])
...)
The first kind seems to me useful, and would be easy to implement.
The second is harder (it requires changing the `for' implementation
for the reason I said earlier), and I don't see much practical use of
that.
(A `for' in a lazy language, should be lazy in both ways, of course.)
--
((lambda (x) (x x)) (lambda (x) (x x))) Eli Barzilay:
http://www.barzilay.org/ Maze is Life!
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