# Reference

Ad-hoc material that supports the rest of the book without fitting inside a specific chapter. Dip in when you need a term defined, want to trace what changed between versions, or are curious about the library's performance envelope.

| Page | What it is |
|------|-----------|
| [More Functional Thinking](reading.md) | Recommended reading beyond Higher-Kinded-J: books, papers, and community resources for deepening your functional programming knowledge. |
| [Glossary](glossary.md) | Concise definitions of the terms used throughout the book: HKT, type class, monad, witness, and so on. |
| [Release History](release-history.md) | A version-by-version record of what changed and why. Useful when picking up after an upgrade, or writing your own release notes against a specific version. |
| [Benchmarks & Performance](benchmarks.md) | Empirical measurements of the library's overhead and scaling characteristics, with guidance on when HKT simulation matters and when it doesn't. |

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**Next:** [More Functional Thinking](reading.md)