Stalin (STAtic Language ImplementatioN) is an aggressive optimizing batch whole-program Scheme compiler written by Jeffrey Mark Siskind. It uses advanced flow analysis and type inference and a variety of other optimization techniques to produce code that is very fast, particularly for numerical code.[citation needed] In a number of tests it has outperformed hand-written C, sometimes by a considerable margin.[citation needed] Stalin is intended for production use in generating an optimized executable.

The compiler itself runs slowly, and there is little or no support for debugging or other niceties. Full R4RS Scheme is supported, with a few minor and rarely encountered omissions. Interfacing to external C libraries is straightforward. The compiler itself does lifetime analysis and hence does not generate as much garbage as might be expected, but global reclamation of storage is done using the Boehm garbage collector.