Forth Interpreter (Elixir)

This project is a full-featured Forth interpreter built with Elixir, integrated into a Phoenix LiveView application with PostgreSQL database persistence.

Overview

The application allows users to write Forth programs, evaluate them in real-time, and automatically persist the execution history in a database.

Architecture

• Core Logic: Pure Elixir module (Forth.eval/2) handling token parsing, stack operations, and strict error handling (e.g., stack underflows, division by zero). Cleanly integrated into the application's domain logic in lib/forth_interpreter_elixir/forth.ex.
• Web Interface: A reactive single-page application built with Phoenix LiveView for instant user feedback.
• Persistence: PostgreSQL database integrated via Ecto to store and display the history of all evaluations.

Supported Language Features

• Integer Arithmetic: +, -, *, /
• Stack Manipulation: DUP, DROP, SWAP, OVER
• Custom Words: Definition of new words using the standard syntax (: word-name definition ;).

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1. Prerequisites

Ensure you have the following installed on your system:

• Elixir (1.18 or later)
• Erlang/OTP (27 or later)
• PostgreSQL (Running locally)

2. Compilation & Setup

Before running the application for the first time, you must install dependencies and setup the database.

# Install dependencies
mix deps.get

# Setup the database (create and migrate)
# Note: Ensure your DB credentials in config/dev.exs are correct
mix ecto.setup

3. Running the Application

To start the Phoenix LiveView interface:

# Start the server
mix phx.server

Once started, you can access the interface at http://localhost:4000.

4. Running Tests

The project includes a comprehensive test suite for both the core Forth logic and the web components. Bash

# Run all tests
mix test

5. Using the Program

Input: Type your Forth code into the "Program Input" text area. (Example: 1 2 + 3 *)

Action: Click the Evaluate button to process the code.

Results: The current result (stack state or error message) will appear immediately below the input area.

History: Every evaluation is automatically saved to the PostgreSQL database and displayed in the history table at the bottom of the page.