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## 3.4.7 Defsetf Lambda Lists

A defsetf lambda list is used by defsetf.

A defsetf lambda list has the following syntax:

    lambda-list::= (var*
                    [&optional {var | (var [init-form [supplied-p-parameter]])}*]
                    [&rest var]
                    [&key {var | ({var | (keyword-name var)} [init-form [supplied-p-parameter]])}* [&allow-other-keys]]
                    [&environment var]

A defsetf lambda list can contain the lambda list keywords shown in the next figure.

    &allow-other-keys  &key       &rest
    &environment       &optional

Figure 3-19. Lambda List Keywords used by Defsetf Lambda Lists

A defsetf lambda list differs from an ordinary lambda list only in that it does not permit the use of `&aux`, and that it permits use of `&environment`, which introduces an environment parameter.

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