Pascal Bourguignon wrote:

> > > An intelligent implementation could avoid reading the file.
> > > But otherwise, the answer is that it's not possible portably.
> > > Drop down to the POSIX API.
> >
> > How does one do that? Is there an example somewhere?
>
> (defun file-length-in-bytes (file)
> ;; Note the "EXT" implementation specific package.
> (with-open-stream (in (ext:run-program "/bin/ls"
> :arguments (list "-l" (namestring file))
> :output :stream))
> (read in)(read in)(read in)(read in)(read in)))
>
> Alternatively, one could use FFI:
>
> (defun file-length-in-bytes (file)
> (multiple-value-bind (res stat) (linux:stat (namestring file))
> (linux:|stat-st_size| stat)))

Gauche Scheme:

(use file.util)
(file-size "data.txt")