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128 lines
5.5 KiB
Markdown
128 lines
5.5 KiB
Markdown
| Lama 1.3 |
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| [![Lama 1.3][1]][2] |
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[1]: https://github.com/PLTools/Lama/Lama/workflows/Build/badge.svg?branch=1.30
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[2]: https://github.com/PLTools/Lama/Lama/actions
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# Lama
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 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.
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Its general characteristics are:
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* procedural with first-class functions - functions can be passed as arguments, placed in data structures,
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returned and "constructed" at runtime via closure mechanism;
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* with lexical static scoping;
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* strict - all arguments of function application are evaluated before a function body;
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* imperative - variables can be re-assigned, function calls can have side effects;
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* untyped - no static type checking is performed;
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* with S-expressions and pattern-matching;
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* with user-defined infix operators, including those defined in local scopes;
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* with automatic memory management (garbage collection).
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The name  is an acronym for *Lambda-Algol* since the language has borrowed the syntactic shape of operators from **Algol-68**; [**Haskell**](http://www.haskell.org) and [**OCaml**](http://ocaml.org) can be mentioned as other languages of inspiration.
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The main purpose of  is to present a repertoire of constructs with certain runtime behavior and relevant implementation techniques.
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The lack of a type system (a vital feature for a real-world language
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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.
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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).
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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  itself.
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In addition, a source-level reference interpreter is implemented as well as a compiler to a small stack machine.
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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.
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## Language Specification
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The language specification can be found [here](lama-spec.pdf).
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## Installation
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Supported target: GNU/Linux x86_64, MacOS x86_64 (arm using Rosetta).
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***Windows*** users should get Windows Subsystem for Linux a.k.a WSL (recommended) or cygwin.
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Ubuntu-based variant of WSL is recommended.
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* System-wide prerequisites:
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- Linux: `gcc`
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For example, (for Debian-based Linux):
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```bash
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sudo apt install gcc
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```
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- MacOS: `clang`
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Should be automatically installed with developer tools.
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- [opam](http://opam.ocaml.org) (>= 2.0.4)
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- [OCaml](http://ocaml.org) (>= 4.10.1). *Optional* because it can be easily installed through opam.
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Compiler variant with `flambda` switch is recommended.
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* Check that `opam` is installed (using commands `which opam` or `opam --version`)
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**Installation guide**
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1. Install the right [switch](https://opam.ocaml.org/doc/Manual.html#Switches) for the OCaml compiler
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```bash
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opam switch create lama --packages=ocaml-variants.4.14.2+options,ocaml-option-flambda
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```
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* In the above command:
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- `opam switch create` is a subcommand to create a new switch
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- `ocaml-variants.4.14.2+options` is the name of a standard template for the switch
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- `lama` is an alias for the switch being created; on success a directory `$(HOME)/.opam/lama` should be created
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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`)
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```bash
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eval $(opam env --switch=lama --set-switch)
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```
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* 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
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```
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The OCaml compiler, version 4.14.2
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Standard library directory: /home/user/.opam/lama/lib/ocaml
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```
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3. Pin Lama package using `opam` and right URL (remember of "#" being a comment character in various shells)
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```bash
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opam pin add Lama https://github.com/PLTools/Lama.git\#1.30 --no-action
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```
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The extra '#' sign is added because in various Shells it is the start of a comment
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4. Install dependencies on system-wide external packages and `lama` itself after that.
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```bash
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opam install Lama --yes
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```
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5. Check that `lamac` executable was installed: `which lamac` should answer with
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```
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/home/<USER>/.opam/lama/bin/lamac
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```
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### Smoke-testing (optional)
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Clone the repository and run `make -C tutorial`.
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It should build a local compiler `src/lamac` and a few tutorial executables in `tutorial/`.
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### Useful links
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* [Plugin for VS Code](https://marketplace.visualstudio.com/items?itemName=mrartemsav.lama-lsp)
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### Changes in Lama 1.3
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* Migrated from x86-32 to x86-64 architecture.
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* Added `let ... in ...` construct.
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* Added `-g` mode
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* Changed regex syntax ...
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### Changes in Lama 1.2
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* New garbage collector: single-threaded stop-the-world `LISP2` (see GC Handbook for details: [1st edition](https://www.cs.kent.ac.uk/people/staff/rej/gcbook/), [2nd edition](http://gchandbook.org/)) [mark-compact](https://www.memorymanagement.org/glossary/m.html#term-mark-compact).
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