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Testing Whether A File Is A Directory

Problem

You have a list of file names, which includes the names of some directories. You want to test if a name refers to a file or directory.

Solution

There are two predicates that are useful here: file-exists?, which returns #t if a file name corresponds to a file, but not to a directory, and directory-exists?, which returns #t if a file name corresponds to a directory, but not to a file. You can use directory-exists? with directory-list and filter to create a list of file names that correspond only to directories:

("CVS" "index.ss" "make-site.ss" "schema.ss" "site.ss" "style.css" "write-site.ss")
> (file-exists? "CVS")
#f
> (directory-exists? "CVS")
#t
> (require (lib "list.ss"))
> (filter directory-exists? (directory-list))
("CVS")

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Contributors

-- NoelWelsh - 14 May 2004