Often, a means of creating a function is with lambda notation. Many languages with
functional features use the word "lambda" as the name of the operator, but Haskell uses
the backslash character (because it looks somewhat similar to the Greek letter, lambda).
A lambda notation looks much like a type signature. The arrow indicates that a lambda
notation describes a function from one type of thing (the thing following the backslash)
to another type of thing (whatever follows the arrow).