uiop:file-exists-p

(uiop:file-exists-p pathname)

Answers whether a file exists: the pathname when it does, nil when it does not. It is exactly probe-file under its ASDF/UIOP name -- same contract, same behavior -- and it lowers onto that primitive on every backend, so libraries spelling the question the UIOP way (postmodern's execute-file, for instance) need no shim.

The "truename" answered on success is a pathname carrying the argument namestring: no backend resolves symbolic links or makes the path absolute. A directory counts as existing.

Backend support

Works on all four backends. The interpreter registers a global function delegating to probe-file; the compile paths rewrite the one-argument call into a direct probe-file call.