ANSI Common Lisp 3 Evaluation and Compilation 3.4 Lambda Lists 3.4.4 Macro Lambda Lists
220.127.116.11 Destructuring by Lambda Lists
Anywhere in a macro lambda list where a parameter
name can appear, and where ordinary lambda list syntax
(as described in Section 3.4.1 Ordinary Lambda Lists) does not
otherwise allow a list, a destructuring lambda list
can appear in place
of the parameter name. When this is done, then the argument
that would match the parameter is treated as a (possibly dotted) list,
to be used as an argument list for satisfying the
parameters in the embedded lambda list.
This is known as destructuring.
Destructuring is the process of decomposing a compound object into
its component parts, using an abbreviated, declarative syntax, rather
than writing it out by hand using the primitive component-accessing
functions. Each component part is bound to a variable.
A destructuring operation requires an object to be decomposed,
a pattern that specifies what components are to be extracted, and the names
of the variables whose values are to be the components.
18.104.22.168.1 Data-directed Destructuring by Lambda Lists
22.214.171.124.2 Lambda-list-directed Destructuring by Lambda Lists