{ V{ 0 0 1 0 1 2 } } [ 4 iota [ iota ] map-concat ] unit-test
{ "abc" } [ "abc" [ 1string ] map-concat ] unit-test
{ { 97 98 99 } } [ "abc" [ 1string ] { } map-concat-as ] unit-test
+
+{ { } } [ { } [ ] [ even? ] map-filter ] unit-test
+{ "bcde" } [ "abcd" [ 1 + ] [ drop t ] map-filter ] unit-test
+{ { 0 4 16 36 64 } } [ 10 iota [ sq ] [ even? ] { } map-filter-as ] unit-test
: map-concat ( ... seq quot: ( ... elt -- ... newelt ) -- ... newseq )
over map-concat-as ; inline
+
+: map-filter-as ( ... seq quot: ( ... elt -- ... newelt ) quot: ( ... newelt -- ... ? ) exemplar -- ... subseq )
+ dup [ selector-for [ compose each ] dip ] curry dip like ; inline
+
+: map-filter ( ... seq quot: ( ... elt -- ... newelt ) quot: ( ... newelt -- ... ? ) -- ... subseq )
+ pick map-filter-as ; inline