In a nutshell,
Ra provides
a modified
R engine
so that code preceded by all jit(1) function call, using his
jit
package from the CRAN archive, will
run faster due to just-in-time compilation of loops and arithmetic
expressions.
Ra offers to pick the low-hanging fruit for users as loops can be a bottleneck. Of course, as shown in Stephen's case study, using appropriate vectorised expression will often be faster still. That said, for a certain class of problems, Ra should offer a decent speed boost.
Debian users can now just say
sudo apt-get install r-base-core-ra r-cran-jit
as the
Ra and
jit
packages in Debian's unstable
distribution (and in the case of jit, even in testing).
Lastly, version 1.1.0 of Ra was released by Stephen yesterday and is now also in Debian unstable.