The Programming Languages Zoo

About the zoo

The Programming Languages Zoo is a collection of miniature programming languages which demonstrates various concepts and techniques used in programming language design and implementation. It is a good starting point for those who would like to implement their own programming language, or just learn how it is done.

The following features are demonstrated:

• functional, declarative, object-oriented, and procedural languages
• source code parsing with a parser generator
• keep track of source code positions
• pretty-printing of values
• interactive shell (REPL) and non-interactive file processing
• untyped, statically and dynamically typed languages
• type checking and type inference
• subtyping, parametric polymorphism, and other kinds of type systems
• eager and lazy evaluation strategies
• recursive definitions
• exceptions
• interpreters and compilers
• abstract machine

Installation

See the installation & compilation instructions.

The languages

The following languages are on display:

miniml_error

like miniml that can also abort execution

minihaskell

lazy, functional, integers, booleans, lists, recursion, statically typed

miniprolog

logic programming, Horn clauses, unification

levy

call-by-push value, statically typed

comm

A procedural language with integer arithmetic, local variables, conditional statements, while loops and print, compiled to simple machine code.

calc

integer arithmetic +, -, *, /

sub

eager, mutable records, statically typed, subtyping

boa

object-oriented, eager, first-class functions, dynamic types, extensible objects

lambda

untyped λ-calculus, several evaluation strategies

calc_var

integer arithmetic +, -, *, /, variables

miniml

eager, functional, recursive functions, statically typed, compiler, abstract machine

poly

lazy, functional, statically typed, parametric polymorphism, type inference

Usage

The languages are not really meant to be used. Rather, you should read and study the source code, which is decorated with ample comments. Also, each language lang has its own README.md and example.lang in the subdirectory src/lang.

Nevertheless, all the language are fully functioning miniature versions of real languages and can be executed. For each language lang you can:

1. see what command-line options are available with

    ./lang.native --help
   

2. run the toplevel with

    ./lang.native
   

3. run files non-interactively with

    ./lang.native <file> <file> ...`
   

4. load files and enter the toplevel

    ./lang.native -l <file> -l <file> ...`
   

Authors

• Andrej Bauer
• Matija Pretnar

License

The project is open source and released under the permissive MIT license.

Contributing

New contributions are welcome. If you would like to contribute to the project, please contact us through the GitHub project page:

• If you discover a problem, open an issue.
• Even better, fix the problem and submit a pull request!
• If you would like to help but do not know how, have a look at open issues and volunteer to resolve one.
• If you have an idea for a new language, we will be happy to take it in. Please note that all the languages are purposely kept simple for educational purposes.

Before you contibute a new langauge, please read these guidelines for contributing.