[Haskell-beginners] first number is a list

Hello, I have to find the first number is a list. So first I tried : let mylast = last [1,2,3,4]mylast This one works but you have to give 2 commands. So i was thinking about using list compreshion. So I did : [x | x <- [1,2,3,4] , last ] But then I see these error : Could not match expected type "Bool" with actual type [a0] -> a0 in the expression last in stdn of a list compreshion last in the expression : [x | x <- [1,2,3,4] , last ] What is my thinking error ? Roelof