Rest

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+

Land

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Rest ⛱️

The High-Performance TypeScript Compiler for Land  🏞️

VS Code's TypeScript build uses tsc with Node.js overhead on every incremental compile. Build times grow linearly with project size. Even alternatives like esbuild still run in a Node.js process.

"VS Code's TypeScript build step. 2-3x faster."

   

Rust API Documentation 📖

Welcome to Rest, a high-performance TypeScript compiler built with Rust and OXC, designed for 100% compatibility with VSCode's build process. Rest is one of the Elements in the CodeEditorLand architecture, responsible for compilation and build tooling. It replaces esbuild's TypeScript loader with a Rust-powered compiler that produces VSCode-compatible output.

Rest is engineered to:

1. Deliver High Performance: Compile TypeScript 2-3x faster than esbuild using OXC.
2. Ensure VSCode Compatibility: Produce byte-for-byte identical output to VSCode's gulp build.
3. Provide Memory Safety: Leverage Rust's ownership model for deterministic performance without garbage collection.
4. Support Modern Tooling: Built on OXC 0.48, the latest TypeScript infrastructure.

Why OXC over esbuild for TypeScript?

The Rest compiler was chosen over the existing esbuild pipeline for three reasons that directly affect the VSCode build:

1. OXC is used by VSCode internally. This means Rest produces output that matches VSCode's own build pipeline - not an approximation.
2. emitDecoratorMetadata support. VSCode's codebase relies on decorator metadata emission. OXC handles this correctly; esbuild has limited support.
3. useDefineForClassFields = false. VSCode requires the legacy class fields behavior for ES5 compatibility. OXC's configurable codegen handles this exactly; esbuild's is implicit.

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Key Features 🔐

• Full TypeScript 5.x Support: Complete compatibility with TypeScript 5.x syntax and features.
• Decorator Handling: Proper support for emitDecoratorMetadata and decorator transformations.
• Class Fields Control: Configurable useDefineForClassFields behavior (VSCode default: false).
• Parallel Compilation: Optional --Parallel flag for multi-core compilation.
• Directory-Based Compilation: Process entire directory structures with preserved layout.
• Comprehensive Error Reporting: Detailed error messages with source location information.
• Compilation Metrics: Built-in tracking of compilation count, elapsed time, and error counts.
• Source Map Generation: Planned support for source maps (in progress).

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Core Architecture Principles 🏗️

Principle	Description	Key Components Involved
Performance	Rust + OXC delivers 2-3x faster compilation than esbuild.	OXC Parser, Transformer, Codegen
Compatibility	OXC is used by VSCode internally, ensuring 1:1 output compatibility.	OXC 0.48, VSCode build process
Memory Safety	No garbage collection, deterministic performance through Rust ownership.	Rust lifetime management
Modern Tooling	Built on the latest OXC infrastructure for TypeScript compilation.	OXC 0.48+

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Deep Dive & Component Breakdown 🔬

To understand how Rest's internal components interact to provide high-performance TypeScript compilation, see the following source files:

• Source/Library.rs - Binary entry point
• Source/Fn/OXC/Compiler.rs - Main compiler orchestration
• Source/Fn/OXC/Parser.rs - OXC parser wrapper
• Source/Fn/OXC/Transformer.rs - AST transformation (decorators, class fields, JSX)
• Source/Fn/OXC/Codegen.rs - Code generation from transformed AST
• Source/Struct/CompilerConfig.rs - Advanced configuration (decorators, class fields, target)

The source files explain the OXC-based compilation pipeline, decorator handling, and VSCode compatibility transformations.

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Rest in the Land Ecosystem ⛱️ +  🏞️

Component	Role & Key Responsibilities
Rest Compiler	High-performance TypeScript to JavaScript compilation.
RestPlugin	esbuild plugin that integrates Rest into the build pipeline.
Build System	Environment-driven compiler selection (esbuild or Rest).

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Getting Started 🚀

Installation 📥

[dependencies]
Rest = { git = "https://github.com/CodeEditorLand/Rest.git", branch = "Current" }

Or use via the Output element's Compiler=Rest environment variable.

Usage 🚀

The Rest compiler is invoked as a CLI binary:

# Compile a directory
rest --input ./Source --output ./Target

# With parallel compilation
rest --input ./Source --output ./Target --Parallel

# Check available options
rest --help

Via the Output element build pipeline:

# Use Rest compiler for TypeScript transpilation
export Compiler=Rest
npm run prepublishOnly

# Development mode with Rest
export NODE_ENV=development
export Compiler=Rest
npm run Run

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See Also

• Rest Documentation
• Architecture Overview
• Why Rust
• Output
• Cocoon

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License ⚖️

This project is released into the public domain under the Creative Commons CC0 Universal license. You are free to use, modify, distribute, and build upon this work for any purpose, without any restrictions. For the full legal text, see the LICENSE file.

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Changelog 📜

Stay updated with our progress! See CHANGELOG.md for a history of changes specific to Rest.

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Funding & Acknowledgements 🙏🏻

Rest is a core element of the Land ecosystem. This project is funded through NGI0 Commons Fund, a fund established by NLnet with financial support from the European Commission's Next Generation Internet program. Learn more at the NLnet project page.

The project is operated by PlayForm, based in Sofia, Bulgaria.

PlayForm acts as the open-source steward for Code Editor Land under the NGI0 Commons Fund grant.

Land	PlayForm	NLnet	NGI0 Commons Fund

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