-- If executes then first block when condition is true if true [say 1]; if true [say 2] [say 3]; -- If executes second block when condition is false if false [say 4] [say 5]; -- If returns nil when without else block say (if false [say 6]); -- If returns block execution value say (if true [7]); say (if false [say 100; 8] [say 200; 9]);