stevensonmt
Issue with initializing nested MapSets
I ran into the following situation when trying to create a MapSet of MapSets yesterday. If you nest the MapSet.new() calls they get flattened. I don’t know if this is a bug or I am just unaware of the reason this should be the expected behavior. Does anyone have an explanation?
iex(1)> MapSet.new(MapSet.new([1,2]))
mapset<[1, 2]>
iex(2)> a = v(1)
mapset<[1, 2]>
iex(3)> MapSet.size(a)
2 # ← expected 1
iex(4)> MapSet.put(MapSet.new(), MapSet.new([1,2]))
mapset<[mapset<[1, 2]>]>
iex(5)> MapSet.size(v(4))
1 # ← this is what I wanted
Marked As Solved
eksperimental
If you want to create a map of one element, you wrap that element in a list like I did, but if Elixir would work as you suggest, if you want to create a map set of 5 elements, how would Elixir know that MapSet.new([1, 2, 3, 4, 5]) is a a map set of 5 elements or a map set of one element which is a list of length 5?
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mudasobwa
What do you mean if? MapSet.new/1 accepts enumerables only as it can be easily seen from the function spec.
Then it iterates through this Enumerable, dedups it and produces a MapSet from unique elements in this Enumerable.
Last Post!
stevensonmt
I’m aware. The rest of the post includes “I think it’s a little odd that MapSet.new requires that the passed arg be enumerable.” @eksperimental explained why it obviously needs to be that way.
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