TypeSpec-Go Emitter - Project Structure and Architecture Discussion

[LarsArtmann]

TypeSpec-Go Emitter - Project Structure and Architecture Discussion

🎯 Executive Summary

This issue defines the comprehensive project architecture for the TypeSpec-Go emitter, based on the complete emitter specification in doc/emitter.md. We need to establish a modern, scalable foundation using Mise task runner and TypeSpec emitter patterns.

📋 Current State

• ✅ Complete specification exists (doc/emitter.md)
• ✅ Basic project structure (README, LICENSE, .gitignore)
• ❌ Zero implementation - greenfield project
• ❌ No development environment setup
• ❌ No build system or testing framework

🏗️ Proposed Architecture

Option 1: Standard TypeSpec Emitter + Mise (RECOMMENDED)

typespec-go/
├── src/
│   ├── index.ts              # Main exports
│   ├── emitter.ts            # Core $onEmit function  
│   ├── options.ts            # Configuration interface
│   ├── lib.ts               # Utility functions
│   ├── generators/
│   │   ├── models.ts        # Model/struct generation
│   │   ├── enums.ts         # Enum generation
│   │   ├── unions.ts        # Union/sealed interface
│   │   ├── operations.ts    # Service interface generation
│   │   └── utils.ts         # Helper functions
│   ├── decorators/
│   │   └── go-decorators.ts # Go-specific decorators
│   └── types/
│       └── go-types.ts      # Type definitions
├── tests/
│   ├── basic.test.ts
│   ├── models.test.ts
│   ├── enums.test.ts
│   └── fixtures/
│       ├── petstore/
│       │   └── main.tsp
│       └── generated/            # Test output
├── mise-tasks/              # Executable task scripts
│   ├── build
│   ├── test
│   ├── lint
│   └── dev
├── mise.toml               # Mise configuration
├── package.json            # npm dependencies only
├── tsconfig.json
└── README.md

Why This Architecture Wins:

1. TypeSpec Compliance - Follows official emitter patterns exactly
2. Mise-Driven - Modern task management, no npm scripts
3. Scalable - Clear separation of concerns
4. Maintainable - Easy to extend and test
5. Professional - Uses industry best practices

🔧 Key Technology Decisions

Mise Task Runner

• ✅ Replaces package.json scripts entirely
• ✅ Task dependencies and conditional execution
• ✅ Environment management and tool versioning
• ✅ Source-based builds (only rebuild when needed)
• ✅ Monorepo-ready for future scaling

TypeScript/Node.js Emitter

• ✅ Official TypeSpec emitter patterns
• ✅ AssetEmitter architecture
• ✅ ESM modules and modern toolchain
• ✅ Comprehensive testing with Vitest

Package Structure

# mise.toml
min_version = "2025.11.2"

[env]
NODE_ENV = "{{ env.NODE_ENV | default(value='development') }}"
PROJECT_NAME = "{{ config_root | basename }}"

[tools]
node = "lts"
typescript = "latest"
"npm:@typespec/compiler" = "latest"
"npm:@typespec/emitter-framework" = "latest"
"npm:vitest" = "latest"
"npm:eslint" = "latest"
"npm:prettier" = "latest"

[tasks.build]
description = "Build TypeScript to dist/"
sources = ["src/**/*.ts"]
outputs = ["dist/**"]
run = "tsc"

[tasks.test]
description = "Run test suite"
depends = ["build"]
run = "vitest run"

[tasks.lint]
description = "Run ESLint"
run = "eslint src/ test/ --max-warnings=0"

[tasks.dev]
description = "Development with watch mode"
run = "tsc --watch"

📊 Implementation Phases

Phase 1: Foundation (Critical Path)

1. Initialize project with Mise and TypeScript
2. Create basic emitter skeleton extending AssetEmitter
3. Set up testing framework with TypeSpec integration
4. Implement namespace-to-package mapping
5. Basic model generation (struct generation)

Phase 2: Core Features (High Impact)

1. Enum generation (string + iota strategies)
2. Union generation (sealed interface pattern)
3. Operation/service generation
4. Go-specific decorators (@go.name, @go.package)
5. Comprehensive testing with real examples

Phase 3: Advanced Features (Professional Polish)

1. HTTP handler generation
2. Validation logic (@minlength, @maxlength, etc.)
3. Advanced TypeSpec features (template models, composition)
4. Performance optimization and benchmarks
5. Documentation and examples

🎯 Immediate Action Items

Priority 1: Project Setup

• Create mise.toml with tasks and tool configuration
• Initialize package.json with TypeSpec dependencies
• Set up TypeScript configuration
• Create basic emitter skeleton
• Set up testing framework

Priority 2: Core Implementation

• Implement namespace-to-package mapping
• Create model struct generation
• Add enum generation logic
• Create union/sealed interface generation
• Add basic operation support

Priority 3: Advanced Features

• Implement Go-specific decorators
• Add HTTP handler generation
• Create comprehensive test suite
• Add performance benchmarks
• Create documentation and examples

🤔 Open Questions

Critical Blocker:

What is the exact TypeSpec emitter development pattern?

We need to understand:

• How to extend @typespec/compiler with emitter classes
• Standard project structure for TypeSpec emitters
• Integration with TypeSpec CLI (tsp compile)
• Core TypeScript dependencies and development patterns

Architecture Questions:

1. Monorepo vs single package? - Start single, scale to monorepo later?
2. Testing strategy? - How to integrate TypeSpec compilation in tests?
3. Performance considerations? - Large TypeSpec files, memory usage?
4. Error handling? - Diagnostic reporting, user experience?

🚀 Success Criteria

MVP Success:

• ✅ Compiles basic TypeSpec to Go models/enums
• ✅ Integrates with TypeSpec CLI
• ✅ Has comprehensive test coverage
• ✅ Follows emitter specification exactly

Production Success:

• ✅ Handles complex TypeSpec features (unions, operations, decorators)
• ✅ Generates production-ready Go code
• ✅ Has real-world examples and documentation
• ✅ Performance suitable for large projects

📚 References

• Complete Specification: doc/emitter.md
• TypeSpec Documentation: https://typespec.io
• Mise Documentation: https://mise.jdx.dev
• Discord Discussion: Archive of TypeSpec-Go emitter planning

🏷️ Labels

• architecture
• project-structure
• mise
• typescript
• typespec
• foundation
• good-first-issue

---

🎯 Call to Action

This issue is ready for immediate implementation. We have:

• ✅ Complete specification to follow
• ✅ Clear architecture defined
• ✅ Modern tooling selected
• ✅ Implementation phases outlined

Next Steps:

1. Approve this architecture 👍/👎
2. Resolve the TypeSpec emitter pattern question
3. Begin Phase 1 implementation

Ready to build the best TypeSpec-Go emitter in the ecosystem! 🚀

[hhhapz]

mostly looks good to me, the only thing is that the mise-tasks directory seems unnecessary, we can just keep all of that in mise.toml

[LarsArtmann]

Work was started with #3