Spec List.(grep-index|first-index|first-rindex)

S32-setting-library/Containers.pod

@@ -255,13 +255,38 @@ an argument will iterate or terminate the C<grep> itself, not some
 loop surrounding the statement containing the C<grep>.  Use a label
 if you mean the other thing.
 
+=item grep-index
+
+ multi method grep-index ( @values: Matcher $test --> List )
+ multi grep-index ( Matcher $test, *@values --> List )
+
+Like C<grep>, but returns a lazy list of ordinal numbers of the matching
+values, or C<Nil> if not found.
+
 =item first
 
  multi method first ( @values: Matcher $test --> Parcel )
  multi first ( Matcher $test, *@values --> Parcel )
 
-C<first> searches exactly like C<grep> but returns only the first matching value, or C<Nil>
-if not found.
+C<first> searches exactly like C<grep> but returns only the first matching
+value, or C<Nil> if not found.
+
+=item first-index
+
+ multi method first-index ( @values: Matcher $test --> Parcel )
+ multi first-index ( Matcher $test, *@values --> Parcel )
+
+Like C<first>, but returns the ordinal number of the first matching value,
+or C<Nil> if not found.
+
+=item first-rindex
+
+ multi method first-rindex ( @values: Matcher $test --> Parcel )
+ multi first-rindex ( Matcher $test, *@values --> Parcel )
+
+Like C<first-index>, but starts checking from the end of the C<List>.  Returns
+the ordinal number of the first matching value (counted from the beginning,
+just as C<first-index>), or C<Nil> if not found.
 
 =item pick