Tip: use a set.
1 2 3 4 5 6 7 8 | ;; Remove elements: (remove #{ 3 5 } [ 1 2 3 4 5 6 7 8 9 ]) ;; Keep elements: (keep #{ 7 5 3 } [ 1 2 3 4 5 6 7 8 9 ]) ;; Check if element exists: (some #{ 5 } [ 1 2 3 4 5 6 7 8 9 ]) |