thousandsofthem
Writing idiomatic Elixir code
Trying to write good elixir code.
Input:
data = %{"a" => 0, "b" => 2, "c" => 0, "evilkey" => 666}
for specific keys i need to write some specific output if condition is true
Ruby version:
out = []
out << "text1" if data["a"] > 0
out << "text2" if data["b"] > 0
out << "text3" if data["c"] > 0
out
Ugly elixir version:
out = []
out = if data["a"] > 0 do
out ++ ["text1"]
else
out
end
...
...
out
Good elixir version: ???
Any thoughts here?
Marked As Solved
thousandsofthem
Thanks!
The solution with filters and map look about right.
Re: IO.iodata_to_binary thing - i can’t just put things together this way, but overall it looks good, just need to add |> Enum.filter(fn(x) -> !is_nil(x) end), i.e.
[
(if data["a"] > 0, do: "text1"),
(if data["b"] > 0, do: "text2"),
(if data["c"] > 0, do: "text3")
] |> Enum.filter(fn(x) -> !is_nil(x) end)
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michalmuskala
You can do that by using if as an expression and assembling list of values finally concatenating them together:
IO.iodata_to_binary([
if(data["a"] > 0, do: "text1", else: ""),
if(data["b"] > 0, do: "text2", else: ""),
if(data["c"] > 0, do: "text3", else: "")
])
You could even extract the if to a separate function, if the pattern if very repeating:
defp if_positive(value, text), do: if(value > 0, do: text, else: "")
IO.iodata_to_binary([
if_positive(data["a"], "text1"),
if_positive(data["b"], "text2"),
if_positive(data["c"], "text3")
])
benwilson512
data
|> Enum.filter(&match?({_, v} when v > 0, &1))
|> Enum.map(fn
{"a", _} -> "text1"
{"b", _} -> "text2"
{"c", _} -> "text3"
end)
taiansu
A more functional apporach
output_texts = %{
"a" => "text1",
"b" => "text2",
"c" => "text3",
}
out = data
|> Enum.filter(fn {_, v} -> v > 0 end)
|> Enum.filter(fn {k, _} -> Enum.member(Map.keys(output_texts), k) end)
|> Enum.map(fn {k, _} -> output_texts[k] end)
|> Enum.join()Popular in Questions
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