SR (pronounced "es-ar") is a statically typed, imperative programming language designed for systems programming. It was created in the early 1970s by David Gries and James Horning at Cornell University.
SR is known for its simple syntax and semantics, and for its support of multiple programming paradigms. It is also notable for its use of garbage collection and for its exception handling mechanism, which allows programmers to handle errors in a consistent way.
SR has been used in a variety of systems, including the operating system kernels of IBM's AIX and z/OS, the Plan 9 operating system from Bell Labs, and the Inferno operating system from Lucent Technologies. It has also been used in a number of commercial applications, such as the Interlisp programming environment and the DART real-time operating system.