Type classes first appeared in the Haskell programming language. Do you have any idea why this is not working? Atoms can contain any character if they are enclosed within single quotes and an escape convention exists which allows any character to be used within an atom. The syntax {D1,D2,...,Dn} denotes a tuple whose arguments are D1, D2, ... Dn. Initially composing light-hearted and irreverent works, he also wrote serious, sombre and religious pieces beginning in the 1930s.