A generic function lambda list is used to describe the overall shape of the argument list to be accepted by a generic function. Individual method signatures might contribute additional keyword parameters to the lambda list of the effective method.
A generic function lambda list is used by defgeneric.
A generic function lambda list has the following syntax:
lambda-list ::=({var}*
[
&optional {var | (var)}*]
[
&rest var]
[
&key {var | ({var | (keyword-name var)})}* pt [&allow-other-keys
]]
)
A generic function lambda list can contain the lambda list keywords shown in Figure 3–14.
&allow-other-keys &optional &key &rest Figure 3–14: Lambda List Keywords used by Generic Function Lambda Lists
A generic function lambda list differs from an ordinary lambda list in the following ways:
Zero or more required parameters must be specified.
Optional parameters and keyword parameters may not have default initial value forms nor use supplied-p parameters.
The use of &aux is not allowed.