This blog is updated daily.
A general description is here.
HTML help is now generated dynamically using an HTTP server running in the R process and listening on the loopback interface.
- Those who need to worry about security implications of such a server can disable it by setting the environment variable R_DISABLE_HTTPD to a non-empty value. This disables help.start() and HTML help (so text help is shown instead).
- The Java/Javascript search engine has been replaced by an HTML interface to help.search(). help.start() no longer has an argument 'searchEngine' as it is no longer needed.
- The HTML help can now locate cross-references of the form \link[pkg]{foo} and \link[pkg:foo]{bar} where 'foo' is an alias in the package, rather than the documented (basename of a) filename (since the documneentation has been much ignored).
- Details may change before release.
list.files() (also known as dir()) has a new argument 'include.dirs' to control whether directories are included in the listing: the default of include.dirs = !recursive is unchanged.
A different regular expression engine is used for basic and extended regexps and is also for approximate matching. This is based on the TRE library of Ville Laurikari, a modifed copy of which is included in the R sources.
This is often faster, especially in a MBCS locale.
Some known differences are that it is less tolerant of invalid inputs in MBCS locales, and in its interpretation of undefined (extended) regexps such as "^*". Also, the interpretation of ranges such as [W-z] in caseless matching is no longer to map the range to lower case.
This engine may in future be used in 'literal' mode for fixed = TRUE, and there is a compile-time option in src/main/grep.c to do so.
Basic and extendedExtended (and basic) regexps now support same set of options as for fixed = TRUE and perl = TRUE, including 'useBytes' and support for UTF-8-encoded strings in non-UTF-8 locales.
The algorithm used by strsplit() has been reordered to batch by elements of 'split': this can be much faster for fixed = FALSE (as multiple compilation of regexps is avoided).
New functions memCompress() and memDecopmmpress() for in-memory compression and decompression.
gzfile() looks at the file header and so can now also read bzip2-ed files and xv-comppressed files (where supported).
The check for consistent ordering of superclasses was not ignoring all conditional relations (the symptom was usually spurious warnings for classes extending "array").