Making it fast to create a new hashset

basis/compiler/tree/propagation/transforms/transforms.factor

@@ -135,6 +135,7 @@ IN: compiler.tree.propagation.transforms
     in-d>> first value-info literal>> {
         { V{ } [ [ drop { } 0 vector boa ] ] }
         { H{ } [ [ drop 0 <hashtable> ] ] }
+        { HS{ } [ [ drop f fast-set ] ] }
         [ drop f ]
     } case
 ] "custom-inlining" set-word-prop

core/hash-sets/hash-sets.factor

@@ -22,6 +22,7 @@ M: hash-set clone
     table>> clone hash-set boa ;
 
 M: sequence fast-set <hash-set> ;
+M: f fast-set drop H{ } clone hash-set boa ;
 
 M: sequence duplicates
     HS{ } clone [ [ in? ] [ adjoin ] 2bi ] curry filter ;