- (ecase (sb!kernel:widetag-of fun)
- (#.sb!vm:simple-fun-header-widetag
- (- (sb!kernel:get-lisp-obj-address fun) sb!vm:fun-pointer-lowtag))
- (#.sb!vm:closure-header-widetag
- (fun-address (sb!kernel:%closure-fun fun)))
- (#.sb!vm:funcallable-instance-header-widetag
- (fun-address (sb!kernel:funcallable-instance-fun fun)))))