Stellogen

Note: this project is an experimental proof of concept, not a fully designed and specified programming language.

Stellogen is a logic-agnostic programming language based on term unification. It has been designed from concepts of Girard's transcendental syntax.

Key characteristics

• dynamically/statically typed but without primitive type nor type systems, by using very flexible assert-like expressions defining sets of tests to pass;
• everything is based on term unification;

It is multi-paradigm:

• logic programs are the elementary bricks of computation and typing;
• functional programs correspond to logic programs enforcing an order of interaction;
• imperative programs are iterative recipes constructing logic programs;
• objects are ways to structure logic programs.

Influences

It draws (or try to draw) inspiration from:

• Prolog/Datalog (for unification-based computation);
• Smalltalk (for message-passing, object-oriented paradigm and minimalism);
• Coq (for proof-as-program paradigm and iterative programming with tactics);
• Scheme/Racket (for minimalism and metaprogramming);
• Haskell/Ruby/Lua (for syntax).

Syntax samples

Finite state machine

spec binary =
  -i(e) ok;
  -i(0:X) +i(X);
  -i(1:X) +i(X).

e :: binary.
e = +i(e).

000 :: binary.
000 = +i(0:0:0:e).

010 :: binary.
010 = +i(0:1:0:e).

110 :: binary.
110 = +i(1:1:0:e).

a1 = galaxy
  initial =
    -i(W) +a(W q0).
  final =
    -a(e q2) accept.
  transitions =
    -a(0:W q0) +a(W q0);
    -a(0:W q0) +a(W q1);
    -a(1:W q0) +a(W q0);
    -a(0:W q1) +a(W q2).
end

show process #e.   #a1. #kill. end
show process #000. #a1. #kill. end
show process #010. #a1. #kill. end
show process #110. #a1. #kill. end

More examples can be found in examples/.

Learn

This project is still in development, hence the syntax and features are still changing frequently.

To learn more about the current implementation of stellogen:

• French guide (official): https://tsguide.refl.fr/
• English guide: https://tsguide.refl.fr/en/

Use

You can either download a released binary (or ask for a binary), install using opam, or build the program from sources.

Install using opam

Install opam.

Install the latest development version of the package from this repo with

opam pin tsyntax https://github.com/engboris/stellogen.git

Build from sources

Install opam and OCaml from opam : https://ocaml.org/docs/installing-ocaml

Install dune:

opam install dune

Install dependencies

opam install . --deps-only --with-test

Build the project

dune build

Executables are in _build/default/bin/.

Build from sources using Nix

Install dependencies

nix develop

Build the project

dune build

Executables are in _build/default/bin/.

Commands

Assume the executable is named sgen.exe. Interpreter Stellogen programs with:

./sgen.exe <inputfile>

or if you use Dune:

dune exec sgen -- <inputfile>