pathnamep

(pathnamep object)

Whether object is a pathname -- the distinct value #P"..." denotes, an object carrying its namestring. A string is NOT one (it merely DESIGNATES a pathname, as in standard Common Lisp), and neither is any other value. It agrees with (typep object 'pathname), as Common Lisp requires the two to.

The producers -- pathname, make-pathname, merge-pathnames, probe-file, truename, directory and the uiop: directory walkers -- all answer pathnames, and every path-taking operator accepts a pathname and a namestring alike, so the predicate is what lets a library tell a FILE from TEXT: (typecase in (pathname (open in)) (t ...)) opens a #P"..." argument and parses a string argument as content.

(pathnamep "/tmp/data.json") and (pathnamep 42) are NIL.