Tooling: Build-Time Safety for Higher-Kinded-J

"Make illegal states unrepresentable." -- Yaron Minsky

Every Path type in Higher-Kinded-J can only chain with the same type. Mix a MaybePath into an EitherPath chain, and you get an IllegalArgumentException at runtime. The code compiles; the tests pass (until someone hits that branch); production breaks at 2 AM.

The HKJ tooling catches these mistakes before your code ever runs. Both Gradle and Maven are supported with dedicated build plugins.

In This Chapter

  • Build Plugins -- One-line setup for Gradle or Maven that configures dependencies, preview features, and compile-time checks automatically. Replaces multi-block boilerplate configuration with a single plugin application.

  • Compile-Time Checks -- A javac plugin that detects Path type mismatches at compile time, preventing runtime IllegalArgumentException errors. Follows a strict no-false-positives policy.

  • Diagnostics -- The hkjDiagnostics Gradle task or mvn hkj:diagnostics Maven goal that reports your current HKJ configuration, showing exactly which dependencies, compiler arguments, and checks are active.

Chapter Contents

  1. Build Plugins - One-line project setup for Gradle and Maven
  2. Compile-Time Checks - Path type mismatch detection
  3. Diagnostics - Configuration reporting and troubleshooting

Next: Build Plugins