Please Lang

Made by Daniel del Castillo de la Rosa

This respository contains a language called Please. This language has been designed to run on top of JavaScript, mimicking the Egg language.

Installation

You can install the language like this:

npm i -g @ull-esit-pl-2021/please-Daniel-del-Castillo

You can also install locally.

Use

From the CLI

There is a main executable please that acts as compiler and interpreter. Please is an interpreted language, but it can be sort of compiled to a JSON AST. Below the help the please executable help:

Usage: please [options] [command]

A simple programming language built on top of JavaScript

Options:
  -V, --version           output the version number
  -h, --help              display help for command

Commands:
  repl                    Run the Please lang repl
  run|r <fileName>        Run a Please lang file
  compile|c <origin>      compile a Please lang file
  interpret|i <fileName>  interpret a compiled Please lang file
  transpile|t <fileName>  transpile a Please lang file to JS
  help [command]          display help for command

The subcommands can also be used as executables and are also exported. Each subcommand also has its own help. It is possible to compile the Please file to a compiled format, to interpret a compiled Please file, to run a Please file and to transpile a Please file to JavaScript. The transpiled files are minified and bundled with the necessary dependencies so they can be executed as standalone files, but is possible to transpile to a intermediate JS representation with the -l option. Keep in mind the file produced this way won't work on their own, this option is only provided for the case that you want to inspect this intermediate representation.

From code

The module exports the following functions:

module.exports = {
  interpret,
  interpretFromFile,
  run,
  runFromFile,
  topScope,
  keywords,
  Value,
  Word,
  Call,
  MethodCall,
  parse,
  parseCall,
  parseExpression,
  parseFromFile,
  compile,
  Lexer,
  jsonToASTMap,
  jsonToAST,
  convertToJS,
  convertToJSFromCompiledFile,
  convertToJSFromFile,
  transpile,
  transpileFromCompiled,
};

You can check what each of them does in the documentation.

Documentation

The code is extensively documented. The generated documentation can be consulted here

Features

The Please language has severals features:

• While loops
• If else constructs
• Functions (closure-like)
• Arrays
• Currying
• For loops
• Foreach loops
• Objects
• Hashes
• Regular expressions

There are examples inside the test folder for each of these ones

Indexes work differently if used inside [] or with the element function or sub method. In the latter they work like ruby indexes, meaning if you use a negative index it will start counting from the end, but in the normal brackets negative indexes aren't allowed in arrays. With brackets they work as expected in objects with negative integers as keys.

Contribution

You can contribute to the code if you want! Just keep in mind this isn't a serious project and that your code will be under release to the public domain, because this project uses Unlicense