OCaml

1. The Core Language

   Functions, data types, pattern matching, records, variants, and references.

2. The Module System

   Modules, signatures, functors, and separate compilation.

3. Objects and Classes

   Objects, classes, and inheritance in OCaml.

4. Labels and Variants

   Labeled and optional arguments and polymorphic variants.

5. Polymorphism and Its Limitations

   Let-polymorphism, the value restriction, and weak types.

6. GADTs

   Generalized algebraic data types and type refinement.

7. Parallel Programming (Multicore)

   Domains, parallelism, and memory model in OCaml 5.

8. Effect Handlers

   User-defined effects and handlers.

9. Interfacing with C

   Foreign function interface and external declarations.

10. Dune and Tooling

    Building OCaml projects with dune.

Each section links to the official page. Titles and summaries by Extra Credit; the docs belong to their authors.