Large, no worries mutable maps for Elixir. These MutableMaps can be used as drop-in replacements for Maps, but can also be used as a shared, mutable, concurrent data store.

Multiple processes can safely read and write to the same MutableMap without the need for locking or other synchronization mechanisms. When no process is using the MutableMap anymore, it is automatically garbage collected like normal Elixir Maps.

When working with large data sets, Elixir's Maps and Keywords can become unwieldy. E.g. when using large maps (200mb+) then sending them between processes becomes really slow (Easily 50ms and more for one send(pid, large_map)). On the other hand Erlang :ets tables can solve this problem, but their API is unwieldy and they require explicit creation and cleaning up.

Instead MutableMaps offer an easy to use, performant and most importantly lazy garbage collected data storage solution.

# Create a new MutableMap
MutableMap.new()

# Create a new MutableMap from a list
MutableMap.new([{1, 2}, {3, 4}])

# Set and get values
MutableMap.put(map, 1, 2)
MutableMap.get(map, 1)

# Delete values
MutableMap.delete(map, 1)

# Since MutableMaps are mutable they can be explicitly copied to create different instances

map1 = MutableMap.new()
map2 = map1
MutableMap.put(map1, :a, 1)
MutableMap.to_list(map1)
# => [:a, 1]
MutableMap.to_list(map2)
# => [:a, 1]
map3 = MutableMap.new(map1)
MutableMap.put(map3, :b, 2)
MutableMap.to_list(map1)
# => [:a, 1]
MutableMap.to_list(map3) |> Enum.sort()
# => [:a, 1, :b, 2]

The package can be installed by adding mutable_map to your list of dependencies in mix.exs:

def deps do
  [
    {:mutable_map, "~> 1.0"}
  ]
end