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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:

  • procedural with first-class functions - functions can be passed as arguments, placed in data structures, returned and "constructed" at runtime via closure mechanism;
  • with lexical static scoping;
  • strict - all arguments of function application are evaluated before a function body;
  • imperative - variables can be re-assigned, function calls can have side effects;
  • untyped - no static type checking is performed;
  • with S-expressions and pattern-matching;
  • with user-defined infix operators, including those defined in local scopes;
  • with automatic memory management (garbage collection).

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.

  • System-wide prerequisites:

    • Linux: gcc

      For example, (for Debian-based Linux):

      sudo apt install gcc

    • MacOS: clang

      Should be automatically installed with developer tools.

    • opam (>= 2.0.4)

    • OCaml (>= 4.10.1). Optional because it can be easily installed through opam. Compiler variant with flambda switch is recommended.

  • Check that opam is installed (using commands which opam or opam --version)

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

  • Migrated from x86-32 to x86-64 architecture.
  • Added let ... in ... construct.
  • Added -g mode
  • Changed regex syntax ...

Changes in Lama 1.2