+{ $description "Outputs an assoc removing values that are " { $link f } "." }
+{ $examples
+ { $example "USING: prettyprint assocs hashtables ;"
+ "H{ { 1 f } { 3 4 } } sift-values ."
+ "H{ { 3 4 } }" }
+} ;
+
+{ sift-keys sift-values harvest-keys harvest-values } related-words
+
+HELP: harvest-keys
+{ $values { "assoc" assoc } { "assoc'" "a new assoc" } }
+{ $description "Outputs an assoc removing keys that are empty sequences." }
+{ $examples
+ { $example "USING: prettyprint assocs hashtables ;"
+ "H{ { { 2 } 1 } { { } 3 } } harvest-keys ."
+ "H{ { { 2 } 1 } }" }
+} ;
+
+HELP: harvest-values
+{ $values { "assoc" assoc } { "assoc'" "a new assoc" } }
+{ $description "Outputs an assoc removing values that are empty sequences." }
+{ $examples
+ { $example "USING: prettyprint assocs hashtables ;"
+ "H{ { 1 { } } { 3 { 4 } } } harvest-values ."
+ "H{ { 3 { 4 } } }" }
+} ;
+