Haskell <- list comprehension

So, is the <- in Haskell list comprehension an arrow (as in, ``take the x from''), or does it imitate the ∈ character from the mathematical set notation?
e.g. {x² : x ∈ ℕ} and [x | x <- [0,1..]]).

>>6
My Haskell array is long, hard, and makes it very enjoyable to thrust into my cute japanese girlfriend.