[Haskell-beginners] Print Unicode in String

Hi, Perhaps I'm missing something, but I haven't found an answer to this question in the textbook I have been using (Thompson) or through Google/Hoogle: can a String include Unicode characters? For instance, if I am defining an instance of Show Expr, where Expr models simple arithmetic expressions (or Show Seq, where Seq models a sequent calculus, and so forth), could I define a function *show Pi* = U+03C0 or *show Delta* = U+0395? Perhaps the answer is obvious, but I haven't been able to find it.