John Cowan <xxxxxx@ccil.org> writes:

> I understand what nullary constructors are, but not why they are relevant
> to SRFI 225, which provides no generic constructors of any kind, the
> assumption being that the information required by a constructor is
> arbitrarily different for different dictionary types.

What happens if we remove the last entry from an alist and then add a
new entry? Can this turn it into a plist — or the other way round?

(dict-set! (dict-remove! (λ(x) #t) dict) 1 2)

One thing I’d like to see is an equivalent to assoc, i.e. dict-item:

(dict-item '((1 . 2)) 1)
;; => (1 . 2)
(dict-item '((1 . 2)) 2)
;; => #f

If an entry with the key exists, return the entry in the dictionary (car
as key, cdr as value), if it does not exist, return #f.

This allows distinguishing between value #f and not existing key,
without having to query the datastructure twice.

Best wishes,
Arne
--
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