But how do you know which one is the “first” one?
lud
jhogberg
Erlang Core Team
If you don’t specifically need a map, consider using :gb_trees instead. Its take_smallest/1 and take_largest/1 operations are bound to be quicker than converting to list, sorting, deleting the first entry, and then creating a map again.
6
sodapopcan
stevensonmt
I hadn’t really thought of :gb_trees as “ordered maps” but I suppose that’s more or less what they are. Like others have said I’m curious what the OP’s actual use case is where a random key-value pair being taken out of the map is the desired behavior.
1
benwilson512
Author of Craft GraphQL APIs in Elixir with Absinthe
Yeah this whole exchange is kind of wild.
@docjazither just in case this isn’t abundantly clear: What you’re doing is deleting a random (ish) key from the map. If that’s OK with you then proceed. If it isn’t, please answer one of the several people who asked you to clarify what “first” means to you.
5
msimonborg
I think we all are which is why this thread is still alive 
The sorting solutions and :gb_trees are interesting but I suppose it assumes “first” can be determined by some sorting rules. I’ve been assuming (stress on assuming because we’d all like to know for sure) “first” means “first to be inserted”, the way you might determine the order of a list.
@docjazither If you need a key-value data structure with (atom keys and) precise ordering so that “first” can always be preserved, you might be better of with Keyword lists than with Map. If you are adding or removing elements from your map, the “first” in your enumerations will change. Just beware that Keyword.put/3 inserts new keys at the head of the list, not the tail.
%{}
|> Map.put(:one, "one")
|> Map.put(:two, "two")
|> Map.put(:three, "three")
|> Map.put(:four, "four")
# %{four: "four", one: "one", three: "three", two: "two"}
[]
|> Keyword.put(:one, "one")
|> Keyword.put(:two, "two")
|> Keyword.put(:three, "three")
|> Keyword.put(:four, "four")
|> Enum.reverse()
# [one: "one", two: "two", three: "three", four: "four"]
2
cjbottaro
Sebb
fun fact: since 3.7 python dicts keep insertion order.
No I do not think that we’d want that for Elixir.
2
cjbottaro
msimonborg
Also thanks to this thread TIL that in Elixir small maps (<= 32 elements) automatically sort the keys by Erlang term order, while large maps (> 32 elements) do not!
0