Introduce new operators intended for use by parser combinator libraries.

The expected definitions (which are by no means required) in
parser combinator speak are:

* `p  ~>> f`   =  `bind(p, f)`
* `p1 ~>  p2`  =  `pair_right(p1, p2)`
* `p1 <~  p2`  =  `pair_left(p1, p2)`
* `p1 <~> p2`  =  `pair_both(p1, p2)`
* `p  |~> f`   =  `map(p, f)`
* `1p <|> p2`  =  `either(p1, p2)`

Author: Alex Rønne Petersen

lib/elixir/lib/macro.ex

@@ -17,6 +17,7 @@ defmodule Macro do
     :<, :>, :->,
     :+, :-, :*, :/, :=, :|, :.,
     :and, :or, :when, :in,
+    :~>>, :~>, :<~, :<~>, :|~>, :<|>,
     :<<<, :>>>, :|||, :&&&, :^^^, :~~~]
 
   @doc false
@@ -39,7 +40,8 @@ defmodule Macro do
       o when o in [:&&, :&&&, :and]           -> {:left, 140}
       o when o in [:==, :!=, :=~, :===, :!==] -> {:left, 150}
       o when o in [:<, :<=, :>=, :>]          -> {:left, 160}
-      o when o in [:|>, :<<<, :>>>]           -> {:left, 170}
+      o when o in [:|>, :<<<, :>>>, :~>>, :~>,
+                   :<~, :<~>, :|~>, :<|>]     -> {:left, 170}
       :in                                     -> {:left, 180}
       o when o in [:++, :--, :.., :<>]        -> {:right, 200}
       o when o in [:+, :-]                    -> {:left, 210}

lib/elixir/src/elixir_parser.yrl

@@ -59,6 +59,7 @@ Left     140 and_op_eol.      %% &&, &&&, and
 Left     150 comp_op_eol.     %% ==, !=, =~, ===, !==
 Left     160 rel_op_eol.      %% <, >, <=, >=
 Left     170 arrow_op_eol.    %% < (op), (op) > (e.g |>, <<<, >>>)
+                              %% ~>>, ~>, <~, <~>, |~>, <|>
 Left     180 in_op_eol.       %% in
 Right    200 two_op_eol.      %% ++, --, .., <>
 Left     210 add_op_eol.      %% + (op), - (op)

lib/elixir/src/elixir_tokenizer.erl

@@ -33,10 +33,16 @@
 
 -define(arrow_op3(T1, T2, T3),
   T1 == $<, T2 == $<, T3 == $<;
-  T1 == $>, T2 == $>, T3 == $>).
+  T1 == $>, T2 == $>, T3 == $>;
+  T1 == $~, T2 == $>, T3 == $>;
+  T1 == $<, T2 == $~, T3 == $>;
+  T1 == $|, T2 == $~, T3 == $>;
+  T1 == $<, T2 == $|, T3 == $>).
 
 -define(arrow_op(T1, T2),
-  T1 == $|, T2 == $>).
+  T1 == $|, T2 == $>;
+  T1 == $~, T2 == $>;
+  T1 == $<, T2 == $~).
 
 -define(rel_op(T),
   T == $<;