[erlang-questions] Wanted additions to the maps module?
Björn-Egil Dahlberg XB
Wed Apr 13 15:40:57 CEST 2016
There is currently no (good) way to get out of C-context to execute some
erlang snippet and then get back into c-context. Traps does this but
only in a controlled manner. I think it is doable though.
Your proposal of maps_apply/3 is the maps equivalent of dict:update/3
and sadly that name is already occupied in maps (it's the equivalent of
I think we should add it to the API without thinking about the
performance too much. Performance can always be improved later on.
Is maps:apply/3 the best name we can think of? I don't really trust you
and naming things. =) update/3,4 would probably have been best but c'est
On 2016-04-13 13:09, Jesper Louis Andersen wrote:
> On Fri, Apr 8, 2016 at 8:31 PM, Björn-Egil Dahlberg
> <wallentin.dahlberg@REDACTED <mailto:wallentin.dahlberg@REDACTED>>
> Have you repeated some code or built your own private lib to
> handle certain maps specific tasks and thought "why isn't this in
> the maps module?"
> One function I like to have is "apply update via function", and I
> implement it somewhat often:
> maps_apply(F, K, Map) ->
> V = maps:get(K, Map),
> maps:put(K, F(V), Map).
> But it can be made much faster in a direct implementation since I
> don't have to first pick up the value: I can apply F when I sit with
> the value at hand and thus avoid the "put" lookup path. It might,
> however, be nasty to implement because F is in Erlang-context, whereas
> the maps operations are in BIF-context.
> erlang-questions mailing list
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