This package provides access to the LLVM C++-level API. This allows us to create descriptions of executable code and then generate machine code directly within R. We can then invoke the resulting routines from within R. This essentially allows us to create compiled code dynamically, i.e. on the fly or, in other words, within the R session. We can use this to create compiled Domain Specific Languages or even R itself, directly with R code.
The ability to generate machine-code with a modern, flexible compiler infrastructure has great potential for us within the R community to improve the performance of R-like code. We can use this to build Domain Specific Languages (DSLs) and compile them to machine code. At the simplest, this allows us to turn simple scalar code into machine code and yield enormous speed up, i.e. of a factor of about 200 - 500 relative to interpreted R code for the same element-wise computations.