[Haskell-beginners] Type question

[Paul Johnston]

Hi, I was playing around after getting the new O'Reilly book with lists 
and their operators!
Not sure what the below actually means?

Prelude> [] : []
[[]]
it :: [[a]]

(Got :set +t on )

I thought the first argument of ':' must be an element, so is the empty 
list an element of the same type of the contents of the empty list?

Yours confused Paul :-)