[Haskell-cafe] bottom/unconditionally false in Haskell

I just ran into this formula head = foldr (<<) ⊥ where x << y = x in Bird and Gibbons' *Algorithm Design with Haskell* and I understand it's a sort of pseudo-code. Intuitively, I understand that foldr will take "bottom" as its "starter seed", but I don't know how to convert the << into Haskell code. This works myHead = foldr choose1st undefined where choose1st x y = x but I can't get myHead2 = foldr (<<) undefined where << x y = x to work. How do you create a non-alphanumeric operator like <