Documentation

Introduction

Getting started — Install Vary and write your first program
Syntax overview — A guided tour of Vary's syntax and features
CLI reference — Commands for running, testing, formatting, and building
Configuration — Project settings via vary.toml
Project layout — Recommended directory structure for Vary applications
Quick reference — Daily command sequences for Vary development
FAQ: Frequently asked questions — Common questions about the language and toolchain
Glossary — Plain-English definitions for verification, compiler, and language jargon

Types — Primitives, optionals, function types, and type inference
Classes and data types — Classes for mutable state, data types for immutable values
Generics — Write type-safe code that works with any type
Enums and pattern matching — Fixed variant types with payloads and pattern matching
Collections and strings — Lists, dicts, sets, and string operations
Error handling — Try/except, Result types, and custom error classes
Modules and imports — File-based modules, imports, and package structure
Concurrency — Spawn tasks, manage task groups, and handle cancellation
Contracts — Preconditions and postconditions on functions

Built-in functions — Functions available everywhere without imports
Standard library — Importable modules for JSON, crypto, filesystem, HTTP, time, process, env, logging, and more

Check rules — Reference for all vary check diagnostic rules, categories, and auto-fixes
Testing — Built-in test blocks with observe assertions and property-based testing
CI verification — Set up GitHub Actions for Vary projects with verification profiles

Python comparison — Side-by-side syntax and semantics comparison with Python
Hypothesis comparison — How Vary's across-based property testing compares to Hypothesis for Python
Related languages — Languages that influenced Vary's design

Writing Vary with LLMs — Using AI coding tools to write Vary programs
LLM coding checklist — Do-this / don't-do-this rules for LLM coding assistants writing Vary

Varyonic programming — The design philosophy of Vary: observable behaviour, typed domains, pure logic, and verification-first architecture
Language design choices — Trade-offs and rationale behind language decisions
The compiler — How the compiler pipeline turns source into bytecode
Performance — Benchmark results comparing Vary to Java and Python
Ecosystem — Tools, extensions, and integrations around Vary
What we ship — Distribution formats and what each release includes

Embedded DSLs — Compiler-integrated DSLs for SQL, HTTP, structured logging, and JSON decode
HTTP services — Expose interfaces as HTTP services with typed routes
SQLite databases — Built-in SQLite support with compile-time typed queries
Structured logging — Typed, mutation-aware logging with pluggable sinks
JSON decode — Typed JSON extraction with path-aware errors, validation predicates, and the ? operator