DEFLISTTYPE : UTILITYDEFLISTTYPE is an utility.
DEFLISTTYPE is a macro that expands into a deftype%.
(DEFLISTTYPE list-type single-type rest-props) defines the type of
lists with elements of type single-type. rest-props can be used to
override any inherited attributes from the single-type, typically
used for the MHELP property.
In an alternative form, one can write (DEFLISTTYPE list-type
single-type (OTHER-KEYS (test form ...) (test form ...) ...) rest-props)
where form ... is executed if the corresponding test is non-NIL.
The variable list-type will hold the typed expression. If none of
the tests is true, the usual will be done.
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