This is a Scheme implementation inspired by the excellent book "Structure and Interpretation of Computer Programs" by Abelson and Sussman.

• Implements a subset of the Scheme standard (R5RS) (Revised5 Report on the Algorithmic Language Scheme)
• Automatic memory management (stop-and-copy garbage colletion)
• Proper tail recursion
• Continuations

Tail recursion requires the interpreter to be implemented as a register machine simulator so that we have total control of the execution of the interpreter. Otherwise the interpreter would inherit the control structure of the undelying inplementation (C-language) and could not be tail recursive.

The program contains a scanner and parser for two different languages: for the register machine language and for Scheme. The Scheme interpreter is implemented as a register machine program that is interpreted by the register machine simulator. The Scheme interpreter, in turn, interprets Scheme programs.

Directory old contains old drafts of the interpreter.

Directory bin contains scripts sci.sh (interpreter) and scc.sh (compiler). These are scripts that invoke the register machine simulator with appropriate arguments. sci.sh gives you a REPL, and scc.sh compiles a scheme file given on the command line.

sci.sh can take both scheme files (.scm), and register machine simulator files (.rms) on the command line and run the programs contained within.

• Implemented in C.
• Gnu tools: emacs, make, gcc, gdb
• scanner and parser generators: Gnu versions of lex and yacc (flex, bison)