When writing a natural extension to racket/base for hashes, hash-filter-map, I
found that what would be the most natural way to write it would look like so:
(define (hash-filter-map f ht)
(for/list ([(k v) (in-hash ht)]
#:when/bind [res (f k v)])
res))
Instead I had to write
(define (hash-filter-map f ht)
(for/fold ([result '()])
([(k v) (in-hash ht)]
(cond [(f k v) => (lambda (temp) (cons temp result))]
[else result])))
Which is less pretty.
I'd add this myself, but the for macros are scary. Anyone familiar with this
section of code willing to add this?
-Ian
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