## Generic-function: SB-PCL:SPECIALIZER-TYPE-SPECIFIER [](../) [](../#generic-function) > Return a type specifier for SPECIALIZER, a non-parsed specializer > form or a SPECIALIZER instance. > > More specifically, SPECIALIZER can be > * a non-parsed specializer form such as > * a symbol naming a class > * a list of the form (eql OBJECT) > * a list of the form (SPECIALIZER-KIND &rest SPECIFIC-SYNTAX) > * an instance of a subclass of SPECIALIZER > > When SPECIALIZER cannot be parsed/used as a specializer for > PROTO-GENERIC-FUNCTION and PROTO-METHOD, a STYLE-WARNING is signaled > and NIL is returned. No type declaration will be generated in this > case. > > NIL can also be returned if SPECIALIZER is valid but its type should > not be declared, for example for efficiency reasons. > > NOTE: This generic function is part of an SBCL-specific experimental > protocol. Interface subject to change. ### Lambda list ```cl (sb-pcl::proto-generic-function sb-pcl::proto-method sb-mop:specializer) ```