Indicates the current installed patch level, which is normally zero, but may be updated by patches to DrScheme.
Checks the currently available version on the PLT website (http://download.plt-scheme.org) and returns a value that indicates the current state of the curent installation:
`ok You’re fine.
`(ok-but ,version) You have a fine stable version, but note that there is a newer alpha version available numbered version.
`(newer ,version) You have an old version. Please upgrade to version.
`(newer ,version ,alpha) You have an old-but-stable version, please upgrade to version; you may consider also the newer alpha version numbered alpha.
`(error ,message) An error occurred, and message is a string that indicates the error.
`(error ,message ,additional-info) An error occurred; message is a string that indicates the error, and additional-info is a string containing a system error. The additional-info content is always parenthesizes, so message is a short error and (string-append message " " additional-info) is a verbose one.
The version/tool library implements a DrScheme tool that
makes the patchlevel appears as a version p〈N〉 suffix in DrScheme, though the base verion reported by (version) is not changed);
if enabled by the user, periodically checks whether a new PLT Scheme distribution is available for download.