Ordinarily the result of calling a function is a single object. Sometimes, however, it is convenient for a function to compute several objects and return them.
In order to receive other than exactly one value from a form, one of several special forms or macros must be used to request those values. If a form produces multiple values which were not requested in this way, then the first value is given to the caller and all others are discarded; if the form produces zero values, then the caller receives nil as a value.
Figure 3–5 lists some operators for receiving multiple values_2. These operators can be used to specify one or more forms to evaluate and where to put the values returned by those forms.
| multiple-value-bind | multiple-value-prog1 | return-from |
| multiple-value-call | multiple-value-setq | throw |
| multiple-value-list | return |
The function values can produce multiple values_2.
(values) returns zero values;
(values form) returns the primary value returned by form;
(values form1 form2) returns two values,
the primary value of form1
and the primary value of form2;
and so on.
See multiple-values-limit and values-list.