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?
Also Liked
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.
Popular in Questions
Other popular topics
Latest on Elixir Forum
Sponsor Spotlight
Move fast and fix things! Error tracking with less noise for Elixir devs who love to ship. Start your free dev account.
Categories:
Sub Categories:
Forums
Popular Tags
- #ecto
- #liveview
- #troubleshooting
- #learning-elixir
- #deployment
- #library
- #erlang
- #testing
- #genserver
- #mix
- #absinthe
- #remote-other
- #otp
- #plug
- #how-to-question
- #macros
- #postgres
- #channels
- #elixirconf
- #exunit
- #discussion
- #code-sync
- #javascript
- #podcasts
- #onsite
- #dialyzer
- #docker
- #authentication
- #umbrella
- #full-time-contract
- #podcasts-by-brainlid
- #ecto-query
- #elixir-ls
- #phoenix_html
- #iex
- #blog-post
- #graphql
- #genstage
- #ai
- #websockets
- #supervisor
- #elixirconf-us
- #advent-of-code
- #distillery
- #processes
- #api
- #forms
- #metaprogramming
- #security
- #hex
Our Sponsors
Build Elixir applications with speed and confidence.
Supporting innovation across the BEAM ecosystem.
We build reliable cloud platforms for business-critical systems.
Catch errors, track performance, monitor hosts and more.
Error tracking for Elixir devs who love to ship. Start your free account.
Practical resources that improve the lives of professional developers.
Producing high quality Elixir screencasts since 2017.
Enabling companies to succeed by building software people love.
The team behind Membrane, Popcorn, LiveDebugger. Available for hire.
Courses that'll move you from confusion to "Aha, now I get it!"