The Scheme Vocabulary Scheme's basic vocabulary consists of five categories of words. The five lines in figure show how computer scientists discuss the vocabulary of a language.
All lines employ the same notation.
Dots indicate that there are more things of the same kind in some category. The first category is that of variables, which are the names of functions and values. As indicated before, Scheme has a powerful number system, which is best introduced gradually by examples. The final category is that of primitive operations, which are those basic functions that Scheme provides from the very beginning. While it is possible to specify this collection in its entirety, it is best introduced in pieces, as the need arises.