I'm trying make a lists difference. Found directly prelude operator \\\\ that makes lists difference. But errors Not in scope: '\\\\' occurs. Here is my simple from command line interpreter: Prelude> ([1,2,3] ++ [5,6]) -- works like expected [1,2,3,4,5,6] prelude> ([1,2,3] \\\\ [1,2]) -- erros occurs <interactive>:1:11: Not in scope: "\\\\" Thanks for explanation where I make a mistake.