Using Elixir pipeline to transform a string into a map

Question

Consider the list of string values,

lines = ["foo: 1", "bar: 2", "baz: 3"]

That one might transform into the Elixir map,

%{ "foo": "1", "bar": "2", "baz": "3"}

using a simple Enum.reduce,

Enum.reduce(lines, %{}, fn(line, result) ->
  [key, value] = String.split(line, ": ")
  Map.put(result, key, value)
end)

How might one refactor this into something more succinct, specifically with the third argument passed to reduce? For example, my instinct wants to do something like,

Enum.reduce(lines, %{}, fn(line, result) ->
  String.split(line, ": ") |> Map.put(result)
end)

but the Elixir pipe operator doesn't allow piping multiple values nor piping them to anything other than the first argument.

Answer 1

You can do this with an anonymous function

Enum.reduce(lines, %{}, fn(line, result) ->
  String.split(line, ": ")
  |> (fn(x) -> Map.put(result, hd(x), List.last(x)) end).()
end)

You can also do it like this

Enum.reduce(lines, [], fn(line, result) -> result ++ String.split(line, ": ") end)
  |> Enum.chunk(2)
  |> Map.new(fn [k,  v] -> {k, v} end)

which I less efficient, because it does 2 iterations, but I think it looks cleaner.

Answer 2

This would also be solvable with a map instead of a reduce

lines
|> Enum.map(&String.split(&1, ": "))
|> Map.new(&List.to_tuple/1)