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bug#62068: 29.0.60; map-elt and map-insert for nested structures
From: |
Augusto Stoffel |
Subject: |
bug#62068: 29.0.60; map-elt and map-insert for nested structures |
Date: |
Fri, 10 Mar 2023 08:09:29 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) |
On Fri, 10 Mar 2023 at 02:18, Michael Heerdegen wrote:
> Augusto Stoffel <arstoffel@gmail.com> writes:
>
>> I would like to suggest the following two functions to deal with nested
>> maps. Let me know if you would like to see a patch.
>>
>> (defun map-elt-in (map keys &optional default)
>> "Look up a nested sequence of KEYS in MAP and return its associated value.
>> KEYS is any sequence type supported by `seq'. If a key is not
>> found in any intermediate step, return DEFAULT, which defaults to
>> nil."
>> (catch 'map--break
>> (seq-reduce (lambda (m k)
>> (let ((v (map-elt m k 'map--default)))
>> (if (eq v 'map--default)
>> (throw 'map--break default)
>> v)))
>> keys
>> map)))
>
> Isn't this more or less the same as `map-nested-elt'?
How did I miss that? In any case the more interesting bit is the other
function, which should then be renamed to `map-nested-insert'.
Now, `map-nested-elt' has an inconsistency regarding the DEFAULT
argument which needs to be fixed.
(map-nested-elt '(a nil) '(a) 1)
1
(map-nested-elt '((a . nil)) '(a) 1)
1
etc.
While in the other hand:
(map-elt '(a nil) 'a 1)
nil
(map-elt '((a . nil)) 'a 1)
nil
etc.
Also inconsistent with the rest of Emacs:
(let ((m (make-hash-table)))
(puthash 'a nil m)
(gethash 'a m 1))
nil
(alist-get 'a '((a . nil)) 1)
nil