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Introduction

This document is the formal specification for the Forge programming language, version 0.3.3.

Forge is an internet-native, general-purpose programming language implemented in Rust. It is designed for application-layer work: web services, scripts, data pipelines, prototypes, and tooling. Forge ships with built-in support for HTTP clients and servers, databases (SQLite and PostgreSQL), cryptography, JSON, CSV, terminal UI, AI/LLM integration, and more — eliminating the need for third-party packages for common internet-oriented tasks.

Design Philosophy

Forge is guided by three core principles:

  1. Internet-native. The operations developers perform most frequently — HTTP requests, database queries, JSON parsing, cryptographic hashing — are built into the language and its standard library. A REST API server is four lines. A database query is two.

  2. Dual syntax. Every construct in Forge has two spellings: a classic syntax familiar to developers who have written JavaScript, Python, Rust, or Go; and a natural-language syntax that reads like English prose. Both forms compile to identical internal representations and may be mixed freely within the same source file.

  3. Batteries included. Forge ships 16 standard library modules with over 230 functions, 30 interactive tutorials, a built-in test runner, a formatter, an LSP server, and a project scaffolding tool. A single cargo install provides a complete development environment.

Language Overview

Forge is dynamically typed at runtime with optional type annotations (gradual typing). It supports first-class functions, closures, algebraic data types, pattern matching, Result/Option error handling, structural interfaces, composition via delegation, async/await concurrency, and channels. Programs are executed top-to-bottom without requiring a main function.

The default execution engine is a tree-walking interpreter. A bytecode VM (--vm) and a JIT compiler (--jit) are available for performance-critical workloads but support fewer features.

How to Read This Specification

This specification is organized into five parts:

  • Part I: Language Core covers lexical structure, types, expressions, statements, the type system, error handling, and concurrency.
  • Part II: Standard Library documents each of the 16 built-in modules.
  • Part III: Built-in Functions catalogs all globally available functions.
  • Part IV: Dual Syntax Reference provides the complete mapping between classic and natural syntax forms.
  • Part V: Runtime and Internals describes the interpreter, bytecode VM, JIT compiler, and HTTP server runtime.

Grammar rules are presented in block quotes using an informal EBNF notation. Code examples use forge syntax highlighting. Where both classic and natural syntax exist for a construct, both forms are shown.

Notation Conventions

Throughout this specification:

  • monospace text in prose refers to keywords, operators, or identifiers.
  • Code blocks labeled forge contain valid Forge source code.
  • Grammar productions use → for derivation, | for alternatives, [ ] for optional elements, and { } for zero-or-more repetition.
  • The term “implementation-defined” means the behavior is determined by the specific execution engine (interpreter, VM, or JIT).

Credits

Forge was created by Archith Rapaka / HumanCTO.