Scieneer Common Lisp 1.3.9 online documentation

ext:required-argument [Function]

This function can be used as the default value for keyword arguments that must be always be supplied. Since it is known by the compiler to never return, it will avoid any compile-time type warnings that would result from a default value inconsistent with the declared type. When this function is called, it signals an error indicating that a required keyword argument was not supplied. This function is also useful for defstruct slot defaults corresponding to required arguments.