Move from // to \\

Author: José Valim

CHANGELOG.md

@@ -15,6 +15,7 @@
 
 * Deprecations
   * [Kernel] `binary_to_term/1`, `binary_to_term/2`, `term_to_binary/1` and `term_to_binary/2` are deprecated in favor of their counterparts in the `:erlang` module
+  * [Kernel] `//` for default arguments is deprecated in favor of `\\`. This is a soft deprecation, no warnings will be emitted for it in this release
   * [Record] Deprecate `to_keywords`, `getter` and `list getter` functionalities in `defrecordp`
 
 * Backwards incompatible changes

lib/eex/lib/eex.ex

@@ -105,7 +105,7 @@ defmodule EEx do
       Sample.sample(1, 2) #=> "3"
 
   """
-  defmacro function_from_string(kind, name, source, args // [], options // []) do
+  defmacro function_from_string(kind, name, source, args \\ [], options \\ []) do
     quote bind_quoted: binding do
       info = Keyword.merge [file: __ENV__.file, line: __ENV__.line], options
       args = Enum.map args, fn arg -> { arg, [line: info[:line]], nil } end
@@ -141,7 +141,7 @@ defmodule EEx do
       Sample.sample(1, 2) #=> "3"
 
   """
-  defmacro function_from_file(kind, name, file, args // [], options // []) do
+  defmacro function_from_file(kind, name, file, args \\ [], options \\ []) do
     quote bind_quoted: binding do
       info = Keyword.merge options, [file: file, line: 1]
       args = Enum.map args, fn arg -> { arg, [line: 1], nil } end
@@ -159,15 +159,15 @@ defmodule EEx do
   Get a string `source` and generate a quoted expression
   that can be evaluated by Elixir or compiled to a function.
   """
-  def compile_string(source, options // []) do
+  def compile_string(source, options \\ []) do
     EEx.Compiler.compile(source, options)
   end
 
   @doc """
   Get a `filename` and generate a quoted expression
   that can be evaluated by Elixir or compiled to a function.
   """
-  def compile_file(filename, options // []) do
+  def compile_file(filename, options \\ []) do
     options = Keyword.merge options, [file: filename, line: 1]
     compile_string(File.read!(filename), options)
   end
@@ -181,7 +181,7 @@ defmodule EEx do
       #=> "foo baz"
 
   """
-  def eval_string(source, bindings // [], options // []) do
+  def eval_string(source, bindings \\ [], options \\ []) do
     compiled = compile_string(source, options)
     do_eval(compiled, bindings, options)
   end
@@ -199,7 +199,7 @@ defmodule EEx do
       #=> "foo baz"
 
   """
-  def eval_file(filename, bindings // [], options // []) do
+  def eval_file(filename, bindings \\ [], options \\ []) do
     options  = Keyword.put options, :file, filename
     compiled = compile_file(filename, options)
     do_eval(compiled, bindings, options)

lib/eex/test/eex/smart_engine_test.exs

@@ -20,7 +20,7 @@ defmodule EEx.SmartEngineTest do
     assert_eval "1\n2\n3\n", "<%= lc x inlist [1, 2, 3] do %><%= x %>\n<% end %>"
   end
 
-  defp assert_eval(expected, actual, binding // []) do
+  defp assert_eval(expected, actual, binding \\ []) do
     result = EEx.eval_string(actual, binding, file: __ENV__.file)
     assert result == expected
   end

lib/elixir/lib/application/behaviour.ex

@@ -75,7 +75,7 @@ defmodule Application.Behaviour do
   #     Application.Behaviour.start(:my_app)
   #
   @doc false
-  def start(app, type // :temporary) do
+  def start(app, type \\ :temporary) do
     case :application.start(app, type) do
       { :error, { :not_started, dep } } ->
         case start(dep) do

lib/elixir/lib/behaviour.ex

@@ -122,6 +122,10 @@ defmodule Behaviour do
     raise ArgumentError, message: "default arguments // not supported in defcallback/defmacrocallback"
   end
 
+  defp ensure_not_default({ :\\, _, [_, _] }) do
+    raise ArgumentError, message: "default arguments \\\\ not supported in defcallback/defmacrocallback"
+  end
+
   defp ensure_not_default(_), do: :ok
 
   @doc false

lib/elixir/lib/code.ex

@@ -115,7 +115,7 @@ defmodule Code do
       {3, [a: 1, b: 2]}
 
   """
-  def eval_string(string, binding // [], opts // [])
+  def eval_string(string, binding \\ [], opts \\ [])
 
   def eval_string(string, binding, Macro.Env[] = env) do
     do_eval_string(string, binding, env.to_keywords)
@@ -150,7 +150,7 @@ defmodule Code do
       {3, [a: 1, b: 2]}
 
   """
-  def eval_quoted(quoted, binding // [], opts // [])
+  def eval_quoted(quoted, binding \\ [], opts \\ [])
 
   def eval_quoted(quoted, binding, Macro.Env[] = env) do
     do_eval_quoted(quoted, binding, env.to_keywords)
@@ -225,7 +225,7 @@ defmodule Code do
   `Macro.to_string/2`, which converts a quoted form to a string/binary
   representation.
   """
-  def string_to_quoted(string, opts // []) when is_list(opts) do
+  def string_to_quoted(string, opts \\ []) when is_list(opts) do
     file = Keyword.get opts, :file, "nofile"
     line = Keyword.get opts, :line, 1
     res  = :elixir.string_to_quoted(to_char_list(string), line, file, opts)
@@ -246,7 +246,7 @@ defmodule Code do
 
   Check `string_to_quoted/2` for options information.
   """
-  def string_to_quoted!(string, opts // []) when is_list(opts) do
+  def string_to_quoted!(string, opts \\ []) when is_list(opts) do
     file = Keyword.get opts, :file, "nofile"
     line = Keyword.get opts, :line, 1
     :elixir.string_to_quoted!(to_char_list(string), line, file, opts)
@@ -266,7 +266,7 @@ defmodule Code do
   a given file, the given file will be loaded N times. Check
   `require_file/2` if you don't want a file to be loaded concurrently.
   """
-  def load_file(file, relative_to // nil) when is_binary(file) do
+  def load_file(file, relative_to \\ nil) when is_binary(file) do
     file = find_file(file, relative_to)
     :elixir_code_server.call { :acquire, file }
     loaded = :elixir_compiler.file file
@@ -289,7 +289,7 @@ defmodule Code do
 
   Check `load_file/2` if you want a file to be loaded concurrently.
   """
-  def require_file(file, relative_to // nil) when is_binary(file) do
+  def require_file(file, relative_to \\ nil) when is_binary(file) do
     file = find_file(file, relative_to)
 
     case :elixir_code_server.call({ :acquire, file }) do
@@ -346,7 +346,7 @@ defmodule Code do
 
   For compiling many files at once, check `Kernel.ParallelCompiler.files/2`.
   """
-  def compile_string(string, file // "nofile") when is_binary(file) do
+  def compile_string(string, file \\ "nofile") when is_binary(file) do
     :elixir_compiler.string to_char_list(string), file
   end
 
@@ -357,7 +357,7 @@ defmodule Code do
   the first element is the module name and the second one is its
   binary.
   """
-  def compile_quoted(quoted, file // "nofile") when is_binary(file) do
+  def compile_quoted(quoted, file \\ "nofile") when is_binary(file) do
     :elixir_compiler.quoted quoted, file
   end
 

lib/elixir/lib/dict.ex

@@ -163,7 +163,7 @@ defmodule Dict do
       3
   """
   @spec get(t, key, value) :: value
-  def get(dict, key, default // nil) do
+  def get(dict, key, default \\ nil) do
     target(dict).get(dict, key, default)
   end
 
@@ -286,7 +286,7 @@ defmodule Dict do
 
   """
   @spec merge(t, t, (key, value, value -> value)) :: t
-  def merge(dict1, dict2, fun // fn(_k, _v1, v2) -> v2 end) do
+  def merge(dict1, dict2, fun \\ fn(_k, _v1, v2) -> v2 end) do
     target1 = target(dict1)
     target2 = target(dict2)
 
@@ -322,7 +322,7 @@ defmodule Dict do
 
   """
   @spec pop(t, key, value) :: {value, t}
-  def pop(dict, key, default // nil) do
+  def pop(dict, key, default \\ nil) do
     target(dict).pop(dict, key, default)
   end
 

lib/elixir/lib/dict/behaviour.ex

@@ -50,7 +50,7 @@ defmodule Dict.Behaviour do
   Note you can also test your custom module via `Dict`'s doctests:
 
       defmodule MyDict do
-        def new(keywords // []) do
+        def new(keywords \\ []) do
           ...
         end
       end
@@ -66,7 +66,7 @@ defmodule Dict.Behaviour do
     quote do
       @behaviour Dict
 
-      def get(dict, key, default // nil) do
+      def get(dict, key, default \\ nil) do
         case fetch(dict, key) do
           { :ok, value } -> value
           :error -> default
@@ -133,7 +133,7 @@ defmodule Dict.Behaviour do
         end
       end
 
-      def merge(dict1, dict2, fun // fn(_k, _v1, v2) -> v2 end) do
+      def merge(dict1, dict2, fun \\ fn(_k, _v1, v2) -> v2 end) do
         reduce(dict1, { :cont, dict2 }, fn { k, v1 }, acc ->
           { :cont, update(acc, k, v1, &fun.(k, v1, &1)) }
         end) |> elem(1)

lib/elixir/lib/enum.ex

@@ -209,7 +209,7 @@ defmodule Enum do
   @spec all?(t) :: boolean
   @spec all?(t, (element -> as_boolean(term))) :: boolean
 
-  def all?(collection, fun // fn(x) -> x end)
+  def all?(collection, fun \\ fn(x) -> x end)
 
   def all?(collection, fun) when is_list(collection) do
     do_all?(collection, fun)
@@ -245,7 +245,7 @@ defmodule Enum do
   @spec any?(t) :: boolean
   @spec any?(t, (element -> as_boolean(term))) :: boolean
 
-  def any?(collection, fun // fn(x) -> x end)
+  def any?(collection, fun \\ fn(x) -> x end)
 
   def any?(collection, fun) when is_list(collection) do
     do_any?(collection, fun)
@@ -275,7 +275,7 @@ defmodule Enum do
   """
   @spec at(t, integer) :: element | nil
   @spec at(t, integer, default) :: element | default
-  def at(collection, n, default // nil) do
+  def at(collection, n, default \\ nil) do
     case fetch(collection, n) do
       { :ok, h } -> h
       :error     -> default
@@ -315,7 +315,7 @@ defmodule Enum do
   """
   @spec chunk(t, non_neg_integer, non_neg_integer) :: [list]
   @spec chunk(t, non_neg_integer, non_neg_integer, t | nil) :: [list]
-  def chunk(coll, n, step, pad // nil) when n > 0 and step > 0 do
+  def chunk(coll, n, step, pad \\ nil) when n > 0 and step > 0 do
     limit = :erlang.max(n, step)
 
     { _, { acc, { buffer, i } } } =
@@ -671,7 +671,7 @@ defmodule Enum do
   """
   @spec find(t, (element -> any)) :: element | nil
   @spec find(t, default, (element -> any)) :: element | default
-  def find(collection, ifnone // nil, fun)
+  def find(collection, ifnone \\ nil, fun)
 
   def find(collection, ifnone, fun) when is_list(collection) do
     do_find(collection, ifnone, fun)
@@ -698,7 +698,7 @@ defmodule Enum do
   """
   @spec find_value(t, (element -> any)) :: any | :nil
   @spec find_value(t, any, (element -> any)) :: any | :nil
-  def find_value(collection, ifnone // nil, fun)
+  def find_value(collection, ifnone \\ nil, fun)
 
   def find_value(collection, ifnone, fun) when is_list(collection) do
     do_find_value(collection, ifnone, fun)
@@ -846,7 +846,7 @@ defmodule Enum do
   """
   @spec join(t) :: String.t
   @spec join(t, String.t) :: String.t
-  def join(collection, joiner // "")
+  def join(collection, joiner \\ "")
 
   def join(collection, joiner) when is_binary(joiner) do
     reduce(collection, "", fn
@@ -899,7 +899,7 @@ defmodule Enum do
   """
   @spec map_join(t, (element -> any)) :: String.t
   @spec map_join(t, String.t, (element -> any)) :: String.t
-  def map_join(collection, joiner // "", mapper)
+  def map_join(collection, joiner \\ "", mapper)
 
   def map_join(collection, joiner, mapper) when is_binary(joiner) do
     reduce(collection, "", fn
@@ -1585,7 +1585,7 @@ defmodule Enum do
   """
   @spec uniq(t) :: list
   @spec uniq(t, (element -> term)) :: list
-  def uniq(collection, fun // fn x -> x end)
+  def uniq(collection, fun \\ fn x -> x end)
 
   def uniq(collection, fun) when is_list(collection) do
     do_uniq(collection, [], fun)

lib/elixir/lib/exception.ex

@@ -255,7 +255,7 @@ defmodule Exception do
   calculates a new stacktrace based on the caller and formats it. As
   a consequence, the value of `System.stacktrace` is changed.
   """
-  def format_stacktrace(trace // nil) do
+  def format_stacktrace(trace \\ nil) do
     trace = trace || try do
       throw(:stacktrace)
     catch
@@ -278,7 +278,7 @@ defmodule Exception do
   Notice that due to tail call optimization, the stacktrace
   may not report the direct caller of the function.
   """
-  def format_caller(trace // nil) do
+  def format_caller(trace \\ nil) do
     trace = trace || try do
       throw(:stacktrace)
     catch