reject_reject.ex (1159B)
1 defmodule Credo.Check.Refactor.RejectReject do 2 use Credo.Check, 3 explanations: [ 4 check: """ 5 One `Enum.reject/2` is more efficient than `Enum.reject/2 |> Enum.reject/2`. 6 7 This should be refactored: 8 9 ["a", "b", "c"] 10 |> Enum.reject(&String.contains?(&1, "x")) 11 |> Enum.reject(&String.contains?(&1, "a")) 12 13 to look like this: 14 15 Enum.reject(["a", "b", "c"], fn letter -> 16 String.contains?(letter, "x") || String.contains?(letter, "a") 17 end) 18 19 The reason for this is performance, because the two separate calls 20 to `Enum.reject/2` require two iterations whereas doing the 21 functions in the single `Enum.reject/2` only requires one. 22 """ 23 ] 24 25 alias Credo.Check.Refactor.EnumHelpers 26 27 @doc false 28 def run(source_file, params \\ []) do 29 issue_meta = IssueMeta.for(source_file, params) 30 31 message = "One `Enum.reject/2` is more efficient than `Enum.reject/2 |> Enum.reject/2`" 32 trigger = "|>" 33 34 Credo.Code.prewalk( 35 source_file, 36 &EnumHelpers.traverse(&1, &2, issue_meta, message, trigger, :reject, :reject, __MODULE__) 37 ) 38 end 39 end