09_map_sets.livemd

Elixir Koans - 09 Map Sets

import ExUnit.Assertions

Intro

My name is Set, MapSet.

set = MapSet.new([1, 2, 3, 4, 5])

I do not allow duplication

new_set = MapSet.new([1, 1, 2, 3, 3, 3])

assert MapSet.size(new_set) == ___

You cannot depend on my order

The number "33" is actually special here. Erlang uses a different implementation for maps after 32 elements which does not maintain order. http://stackoverflow.com/a/40408469

def sorted?(set) do
    list = MapSet.to_list(set)
    sorted = Enum.sort(list)
    list == sorted
end

new_set = MapSet.new(1..33)

assert sorted?(new_set) == ___

What do you think this answer to this assertion is?

assert sorted?(set) == ___

Does this value exist in the map set?

assert MapSet.member?(set, 3) == ___

I am merely another collection, but you can perform some operations on me

new_set = MapSet.new(set, fn x -> 3 * x end)

assert MapSet.member?(new_set, 15) == ___

assert MapSet.member?(new_set, 1) == ___

Add this value into a map set

modified_set = MapSet.put(set, 6)

assert MapSet.member?(modified_set, 6) == ___

Delete this value from the map set

modified_set = MapSet.delete(set, 1)

assert MapSet.member?(modified_set, 1) == ___

Are these maps twins?

new_set = MapSet.new([1, 2, 3])

assert MapSet.equal?(set, new_set) == ___

I want only the common values in both sets

intersection_set = MapSet.intersection(set, MapSet.new([5, 6, 7]))

assert MapSet.member?(intersection_set, 5) == ___

Unify my sets

new_set = MapSet.union(set, MapSet.new([1, 5, 6, 7]))

assert MapSet.size(new_set) == ___

I want my set in a list

assert MapSet.to_list(set) == ___

Next Steps

• Previous: Maps
• Next: Structs