Merge pull request #3811 from michalmuskala/optimize_map

Optimize Enum.map/2 for lists Signed-off-by: José Valim <jose.valim@plataformatec.com.br>
elixir-lang · Oct 1, 2015 · 05fecbc · 05fecbc
1 parent 448f473
commit 05fecbc
Showing 1 changed file with 8 additions and 2 deletions.
diff --git a/lib/elixir/lib/enum.ex b/lib/elixir/lib/enum.ex
@@ -1039,8 +1039,14 @@ defmodule Enum do
 
   """
   @spec map(t, (element -> any)) :: list
-  def map(collection, fun) when is_list(collection) do
-    for item <- collection, do: fun.(item)
+  def map(enumerable, fun)
+
+  def map([], _fun) do
+    []
+  end
+
+  def map([head | tail], fun) do
+    [fun.(head) | map(tail, fun)]
   end
 
   def map(collection, fun) do