JupiterIO1
Update value in map based on Enum.member? check
Ultimately I’d like to update the values of keys in myMap based on whether the key is in myList and in myOtherList:
myList = ["a", "b", "c"]
myOtherList = ["b"]
myMap = %{"a" => "no", "b" => "no", "c" => "no"}
Enum.each(myList, fn e ->
case Enum.member?(myOtherList, e) do
true -> Map.replace(myMap, e, "yes")
false -> Map.replace(myMap, e, "no")
end
end)
myMap doesn’t update.
I believe the problem would be because of immutability, but I still cannot arrive to a solution. I’m open to other Map function suggestions.
Marked As Solved
JupiterIO1
The solution was solved in another topic:
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peerreynders
Stop thinking of “variables”- all values in Elixir are immutable. However identifiers can be rebound to new values. So the only thing that can “vary” is the value the identifier is bound to - not the value itself.
Imperative languages are about PLace-Oriented Programming (PLOP) - in functional programming you are programming with values (The Value of Values).
Furthermore you don’t “loop” in Elixir - you recurse.
jgonet
I suggest using if else for this. Also, to mutate your map you have to use explicit assignment, so my_map = if (...).
Oh, and in Elixir snake_case is the most widely used convention.
sanswork
Check out Enum.reduce
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