C--

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C--
Paradigm	imperative
Appeared in	1997
Designed by	Simon Peyton Jones and Norman Ramsey
Typing discipline	static, weak
Influenced by	C

C-- is a C-like programming language. Its creators, functional programming researchers Simon Peyton Jones and Norman Ramsey, designed it to be generated mainly by compilers for very high-level languages rather than written by human programmers. Unlike many other intermediate languages, its representation is plain text, not bytecode or another binary format.

C-- is a "portable assembly language", designed to greatly ease the task of implementing a compiler which produces high-quality machine code by having the compiler generate C-- code, delegating the harder work of low-level code generation and optimisation to a C-- compiler.

Work on C-- began in the late 1990s. Since writing a custom code generator is a daunting challenge in itself, and the compiler back ends available to researchers at that time were complex and poorly documented, several projects had written compilers which generated C code (for instance, the original Modula-3 compiler). However, C is a poor choice for functional languages: it does not support tail recursion, accurate garbage collection or efficient exception handling. C-- is a simpler, tightly-defined alternative to C which does support all of these things. Its most innovative feature is a run-time interface which allows writing of portable garbage collectors, exception handling systems and other run-time features which work with any C-- compiler.

The language's syntax borrows heavily from C. It omits or changes standard C features such as variadic functions, pointer syntax, and aspects of C's type system, because they hamper certain essential features of C-- and the ease with which code-generation tools can produce it.

The name of the language is an in-joke, indicating that C-- is a reduced form of C, in the same way that C++ is basically an expanded form of C. (In C and C++, "--" and "++" are operators meaning "subtract 1 from" and "add 1 to".)

C-- is a target platform for the Glasgow Haskell Compiler, and will eventually become the main platform. Some of C--'s developers, including Simon Peyton Jones, also work on the Glasgow Haskell Compiler. The codebase and development are based at Microsoft Research in Cambridge, though it is not a Microsoft project.

Sphinx C--

The name "C--" was also used for an earlier programming language developed in the 1990s by Peter Cellik for x86 computers. Sphinx C-- mixes C with x86 assembly language.