On Mon, Jul 06, 2015 at 02:50:36PM -0700, Russ Abbott wrote:
> I installed Racket in a directory for which I have access. Yet when I
> attempted to run the example code on the Racket Home page:
>
> (for ([path (in-directory)]
> #:when (regexp-match? #rx"[.]rkt$" path))
> (printf "source file: ~a\n" path))
>
> I got this error message.
>
> Racket\collects\racket\private\for.rkt:1973:2: directory-list: could not open
> directory
> path: C:\Users\facuser\AppData\Local\Application Data
> system error: Access is denied.; errno=5
As coded with no arguments, (in-directory) produces a sequence that will
traverse all files and subdirectories (of the current directory)
recursively [1].
On Windows that runs into permissions problems even in one's own home
directory.
The second argument to in-directory can control the recursion, but to
avoid recursion entirely use directory-list [2] instead:
(for ([path (directory-list)]
#:when (regexp-match? #rx"[.]rkt$" path))
(printf "source file: ~a\n" path))
As a side note, I tried using file-or-directory-permissions [3] to avoid
recursing into directories with no read or execute permission, but it
turns out some directories are inaccessible on Windows even though
file-or-directory-permissions returns '(execute write read). I don't
know enough about Windows permissions to know whether that is expected.
[1]
http://docs.racket-lang.org/reference/sequences.html#(def._((lib._racket/private/base..rkt)._in-directory))
[2]
http://docs.racket-lang.org/reference/Filesystem.html#%28def._%28%28lib._racket%2Fprivate%2Fbase..rkt%29._directory-list%29%29
[3]
http://docs.racket-lang.org/reference/Filesystem.html#%28def._%28%28quote._~23~25kernel%29._file-or-directory-permissions%29%29
David
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