Add factory methods "kept" and "broken" to Promise

Author: timo

doc/Type/Promise.pod6

@@ -19,9 +19,10 @@ combining promises, and waiting for results.
     say $p.status;              # OUTPUT: «Kept␤»
 
 There are two typical scenarios for using promises. The first is to use a
-factory method (C<start>, C<in>, C<anyof>, C<allof>) on the type object; those
-will make sure that the promise is automatically kept or broken for you, and
-you can't call C<break> or C<keep> on these promises yourself.
+factory method (C<start>, C<in>, C<at>, C<anyof>, C<allof>, C<kept>, C<broken>)
+on the type object; those will make sure that the promise is automatically kept
+or broken for you, and you can't call C<break> or C<keep> on these promises
+yourself.
 
 The second is to create your promises yourself with C<Promise.new>. If you
 want to ensure that only your code can keep or break the promise, you can use
@@ -99,6 +100,22 @@ given as an L<Instant> or equivalent L<Numeric>—or as soon as possible after i
 If the given time is in the past, it will be treated as L<now> (i.e.
 L<keeping|/routine/keep> the returned L<Promise> right away).
 
+=head2 method kept
+
+    multi method kept(Promise:U: --> Promise:D)
+    multi method kept(Promise:U: \result --> Promise:D)
+
+Returns a new promise that is already kept, either with the given value,
+or with the default value True.
+
+=head2 method broken
+
+    multi method broken(Promise:U: --> Promise:D)
+    multi method broken(Promise:U: \exception --> Promise:D)
+
+Returns a new promise that is already broken, either with the given value,
+or with the default value "Died".
+
 =head2 method allof
 
     method allof(Promise:U: *@promises --> Promise:D)