add-typep-transformer

Arguments: type function

This function is called for its side effects. The return value has no meaning. This function tells the compiler that a typep form:

    (typep x 'type)

can be transformed into the form:

    (funcall function x)

The compiler will make the transformation where possible.

type must be a type, typically defined by the user with deftype. function should be a function object, a function spec list naming a function, or a symbol naming a function. That function must accept any Lisp object as a single argument and return nil if the object is not of type type, true if it is of type type (that is, the function must be a predicate). remove-typep-transformer removes the transform.

See compiling.htm for general information on compiling and see Adding typep-transformers in that document for more information on typep transforms.

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This page was not revised from the 9.0 page.
Created 2015.5.21.