Add a mnemonic to help remember what's the difference between +:

and :+, plus one for ++:.

2 files changed, 8 insertions, 0 deletions

diff --git a/src/library/scala/collection/GenSeqLike.scala b/src/library/scala/collection/GenSeqLike.scala
index b3dd4764a9..63e9543711 100644
--- a/src/library/scala/collection/GenSeqLike.scala
+++ b/src/library/scala/collection/GenSeqLike.scala
@@ -276,6 +276,8 @@ trait GenSeqLike[+A, +Repr] extends GenIterableLike[A, Repr] with Equals with Pa
   /** A copy of the $coll with an element prepended.
    *
    * Note that :-ending operators are right associative (see example).
+   * A mnemonic for `+:` vs. `:+` is: the COLon goes on the COLlection side.
+   *
    * Also, the original $coll is not modified, so you will want to capture the result.
    *
    *  Example:
@@ -304,6 +306,8 @@ trait GenSeqLike[+A, +Repr] extends GenIterableLike[A, Repr] with Equals with Pa
 
   /** A copy of this $coll with an element appended.
    *
+   *  A mnemonic for `+:` vs. `:+` is: the COLon goes on the COLlection side.
+   *
    *  $willNotTerminateInf
    *  @param  elem   the appended element
    *  @tparam B      the element type of the returned $coll.
diff --git a/src/library/scala/collection/TraversableLike.scala b/src/library/scala/collection/TraversableLike.scala
index 6fa05bd85b..4f0fec1de3 100644
--- a/src/library/scala/collection/TraversableLike.scala
+++ b/src/library/scala/collection/TraversableLike.scala
@@ -159,8 +159,10 @@ trait TraversableLike[+A, +Repr] extends HasNewBuilder[A, Repr]
 
   /** As with `++`, returns a new collection containing the elements from the left operand followed by the
    *  elements from the right operand.
+   *
    *  It differs from `++` in that the right operand determines the type of
    *  the resulting collection rather than the left one.
+   *  Mnemonic: the COLon is on the side of the new COLlection type.
    *
    *  Example:
    *  {{{
@@ -195,8 +197,10 @@ trait TraversableLike[+A, +Repr] extends HasNewBuilder[A, Repr]
 
   /** As with `++`, returns a new collection containing the elements from the
    *  left operand followed by the elements from the right operand.
+   *
    *  It differs from `++` in that the right operand determines the type of
    *  the resulting collection rather than the left one.
+   *  Mnemonic: the COLon is on the side of the new COLlection type.
    *
    *  Example:
    *  {{{