8.5. Standard Procedures

This section describes the expression language's built-in procedures. The initial (or “top-level”) environment starts out with a number of variables bound to useful values, most of which are primitive procedures that manipulate data. For example, the variable abs is bound to a procedure of one argument that computes the absolute value of a number, and the variable + is bound to a procedure that computes sums.

It shall be an error for a procedure to be passed an argument of a type that it is not specified to handle.