GNU Cim is a compiler for the programming language Simula.  It offers
a class concept, separate compilation with full type checking,
interface to external C routines, an application package for process
simulation and a coroutine concept.

The portability of GNU Cim is based on the C programming language.
The compiler and the run-time system is written in C, and the compiler
produces C code, that is passed to a C compiler for further processing
towards machine code.

Homepage:
https://www.gnu.org/software/cim/cim.html
