On 3/21/13 6:55 PM, Tim Nelson wrote:
(1) How can I *not* add a hash entry for a given iteration?
When I use for/list, can I abuse the nature of empty and append* (I
cringe as I write this):
(append* (for/list ([i '(1 2 3 4 5)])
(cond [(even? i) (list (* i 100))]
[else empty])))
Surely there is a better way to do this for for/list, and a way in
general for for/hash?
You can write this equivalently as:
(for/list ([i '(1 2 3 4 5)]
#:when (even? i))
(* i 100))
Which probably answers your for/hash question.
David
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