Add .fmt to (Set|Bag|Mix)(|Hash)

docs/ChangeLog

@@ -17,6 +17,7 @@ New in 2014.05
 + added "subtest code, desc" to Test.pm (inspired by P5's Test::More)
 + Test::Tap::tap_ok and Test::Util::throws_like are now 1 test (using subtest)
 + BagHash<foo>-- on non-existing key no longer fails (as per S02 spec change)
++ (Set|Bag|Mix)(|Hash) now have a .fmt method
 + deprecate $*OS, $*OSVER, $*VM<name>, $*VM<config>, $*PERL<name>
   $*PERL<compiler>...
 + added $*KERNEL, $*DISTRO, $*VM, $*PERL as full blown objects

src/core/QuantHash.pm

@@ -41,6 +41,15 @@ my role QuantHash does Associative {
         }
         @found;
     }
+
+    method fmt(QuantHash: Cool $format = "%s\t\%s", $sep = "\n") {
+        if nqp::p6box_i(nqp::sprintfdirectives( nqp::unbox_s($format.Stringy) )) == 1 {
+            self.keys.fmt($format, $sep);
+        }
+        else {
+            self.pairs.fmt($format, $sep);
+        }
+    }
 }
 
 # vim: ft=perl6 expandtab sw=4