Feeny is a small programming language designed to include the semantics of many popular dynamically-typed programming languages, such as Javascript, Ruby, and Python, and remain simple enough to implement in one semester.
It was first introduced in the University of California, Berkeley graduate course Virtual Machines and Managed Runtimes taught by Mario Wolczko and Patrick S. Li.
The course walks the class through a from-scratch implementation of Feeny, starting with a simple abstract syntax tree interpreter and ending with a just-in-time compiler.
There is an included Feeny parser and implementation written in L.B. Stanza. To compile the system from its sources, you will need to install Stanza. Please go to lbstanza.org to download it. Feeny has been verified to work with version 0.13.44 . Installation instructions for Stanza can be found here.
Run scripts/make-feeny.sh to compile the system. It produces two files: bin/feeny and bin/cfeeny.
The course teaches students to ultimately implement a just-in-time compiler for Feeny through a series of exercises. The exercises are kept in the docs folder.
Evaluating: The following command interprets the included sudoku program.
bin/feeny -e tests/sudoku.feeny
Parsing: The following command reads in the included sudoku program, and outputs the parse tree as a .ast file. The included C files are able to read in .ast files into an in-memory AST datastructure.
bin/feeny -i tests/sudoku.feeny -oast sudoku.ast
Compiling: The following command reads in the included sudoku program, and compiles it to a bytecode .bc format. The included C files are able to read in .bc files.
bin/feeny -i tests/sudoku.feeny -o sudoku.bc
Display an AST File: The following command reads in a .ast file and prints it to the screen.
bin/feeny -past sudoku.ast
Display a Bytecode File: The following command reads in a .bc file and prints it to the screen.
bin/feeny -pb sudoku.bc
Execute a Bytecode File: The following command executes a .bc file.
bin/feeny -rb sudoku.bc
Example AST Interpreter: The example C implementation of the Feeny AST interpreter can be executed using the following command:
bin/cfeeny -ast sudoku.ast
Example Bytecode Interpreter: The example C implementation of the Feeny bytecode interpreter can be executed using the following command:
bin/cfeeny -bc sudoku.bc