ym

Modern Java build tool written in Rust
Drop-in replacement for Maven/Gradle · npm-style DX · Native speed

Features · Installation · Quick Start · Commands · Configuration

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Features

• Yarn + Vite DX — Two binaries: ym (package manager, like Yarn) + ymc (compiler & runtime, like Vite)
• Native Speed — ~5ms startup, incremental build < 3s, 2000 modules IDEA project in 8s
• Zero Config — Declarative package.toml, sensible defaults, no lockfile
• Monorepo Native — Cargo-style { workspace = true }, topological builds, parallel compilation
• Maven Ecosystem — Direct access to Maven Central, reuses .jar / .pom format
• Gradle Migration — ym convert auto-generates package.toml from build.gradle / pom.xml

Why ym?

Installation

One-line install (Linux / macOS / Git Bash):

curl -fsSL https://raw.githubusercontent.com/ympkg/yummy/main/install.sh | bash

Windows PowerShell:

irm https://raw.githubusercontent.com/ympkg/yummy/main/install.ps1 | iex

From crates.io (requires JDK 11+):

cargo install ym

Manual download: grab the latest binary from GitHub Releases and place it in your PATH.

Quick Start

ym init my-app            # Create project (zero questions)
cd my-app
ym add com.google.guava:guava   # Add dependency
ymc build                 # Compile (auto-downloads deps)
ymc dev                   # Compile + run + hot reload
ymc test                  # Run JUnit 5 tests

Commands

Package Manager (ym)

ym init [name]              # Create new project (-i for interactive, -t for template)
ym add <dep>                # Add dependency (auto-fetches latest version)
ym add <dep> --scope test   # Add with scope (compile/runtime/provided/test)
ym remove <dep>             # Remove dependency (fuzzy match supported)
ym upgrade                  # Upgrade dependencies (-i for interactive)
ym convert                  # Convert from Maven/Gradle to package.toml
ym tree                     # Show dependency tree (--depth, --flat, --dot, --reverse)
ym doctor                   # Diagnose environment issues
ym info                     # Show project and environment info
ym publish                  # Publish to Maven registry (--dry-run to preview)
ym login                    # Login to a Maven registry
ym cache clean              # Clean dependency cache (--pattern <p> for selective)
ym workspace list           # List workspace packages
ym workspace foreach -- CMD # Run command in each package (--parallel, --keep-going)
ym <script>                 # Run script from [scripts] in package.toml

Compiler & Runtime (ymc)

ymc build                   # Compile (incremental by default)
ymc build --release         # Build fat JAR for production
ymc build --profile         # Show per-phase timing breakdown
ymc build --keep-going      # Continue on module failure (workspace)
ymc dev                     # Dev mode: compile + run + watch + hot reload
ymc dev --debug             # Dev mode with JDWP debugger (port 5005)
ymc test                    # Run JUnit 5 tests
ymc test --watch            # Watch mode: re-run on change
ymc test --coverage         # Generate JaCoCo coverage report
ymc test --filter "MyTest"  # Filter test classes/methods
ymc test --tag integration  # Run tests by JUnit @Tag
ymc build --clean           # Clean build outputs and rebuild
ymc idea                    # Generate IntelliJ IDEA project files

Configuration

Projects are configured with package.toml:

name = "my-app"
groupId = "com.example"
version = "1.0.0"
target = "21"                    # Java version target

[dependencies]
"com.google.guava:guava" = "33.0.0-jre"
"org.springframework.boot:spring-boot-starter-web" = "3.4.0"
"org.junit.jupiter:junit-jupiter" = { version = "5.11.0", scope = "test" }

[scripts]
hello = "echo Hello from ym!"

[env]
SPRING_PROFILES_ACTIVE = "dev"

Workspace (Monorepo)

# Root package.toml
name = "my-monorepo"
groupId = "com.example"
workspaces = ["modules/*"]

[dependencies]
"com.google.guava:guava" = "33.0.0-jre"

# Module package.toml — inherits from root
[dependencies]
"com.google.guava:guava" = { workspace = true }
"my-other-module" = { workspace = true }       # Inter-module dependency

Migrating from Gradle/Maven

cd my-existing-project
ym convert                   # Auto-generates package.toml from build.gradle or pom.xml

License

MIT