PLTools / Lama

Teaching language LaMa for a compiler course
GNU General Public License v3.0
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compiler ocaml programming-language
Lama 1.3
Lama 1.3

Lama

lama is a programming language (initualy developed by JetBrains Research) for educational purposes as an exemplary language to introduce the domain of programming languages, compilers, and tools. Its general characteristics are:

The name lama is an acronym for Lambda-Algol since the language has borrowed the syntactic shape of operators from Algol-68; Haskell and OCaml can be mentioned as other languages of inspiration.

The main purpose of lama is to present a repertoire of constructs with certain runtime behavior and relevant implementation techniques. The lack of a type system (a vital feature for a real-world language for software engineering) is an intensional decision that allows showing the unchained diversity of runtime behaviors, including those that a typical type system is called to prevent. On the other hand the language can be used in the future as a raw substrate to apply various ways of software verification (including type systems).

The current implementation contains a native code compiler for x86-64, written in OCaml, a runtime library with garbage-collection support, written in C, and a small standard library, written in lama itself.

In addition, a source-level reference interpreter is implemented as well as a compiler to a small stack machine. The stack machine code can in turn be either interpreted on a stack machine interpreter, or used as an intermediate representation by the native code compiler.

Language Specification

The language specification can be found here.

Installation

Supported target: GNU/Linux x86_64, MacOS x86_64 (arm using Rosetta).

Windows users should get Windows Subsystem for Linux a.k.a WSL (recommended) or cygwin. Ubuntu-based variant of WSL is recommended.

Installation guide

  1. Install the right switch for the OCaml compiler

    opam switch create lama --packages=ocaml-variants.4.14.2+options,ocaml-option-flambda
    • In the above command:

      • opam switch create is a subcommand to create a new switch
      • ocaml-variants.4.14.2+options is the name of a standard template for the switch
      • lama is an alias for the switch being created; on success a directory $(HOME)/.opam/lama should be created
  2. Update PATH variable for the fresh switch. (You can add these commands to your ~/.bashrc for convenience but they should be added by opam)

    eval $(opam env --switch=lama --set-switch)
    • Check that the OCaml compiler is now available in PATH by running which ocamlc; it should answer with /home/user/.opam/lama/bin/ocamlc (or similar) and ocamlc -v should answer with
      The OCaml compiler, version 4.14.2
      Standard library directory: /home/user/.opam/lama/lib/ocaml
  3. Pin Lama package using opam and right URL (remember of "#" being a comment character in various shells)

    opam pin add Lama https://github.com/PLTools/Lama.git\#1.30 --no-action

    The extra '#' sign is added because in various Shells it is the start of a comment

  4. Install dependencies on system-wide external packages and lama itself after that.

    opam install Lama --yes
  5. Check that lamac executable was installed: which lamac should answer with

    /home/<USER>/.opam/lama/bin/lamac

Smoke-testing (optional)

Clone the repository and run make -C tutorial. It should build a local compiler src/lamac and a few tutorial executables in tutorial/.

Useful links

Changes in Lama 1.3

Changes in Lama 1.2