Groovy

1. Syntax

   Literals, strings, collections, operators, and comments.

2. Operators

   Arithmetic, safe navigation, elvis, spread, and range operators.

3. Program Structure and Semantics

   Packages, scripts, classes, and imports.

4. Object Orientation

   Classes, traits, interfaces, and inheritance.

5. Closures

   Closure syntax, delegation, currying, and memoization.

6. Groovy Development Kit

   Extensions to Java library classes.

7. Metaprogramming

   Runtime and compile-time metaprogramming and AST transformations.

8. Domain-Specific Languages

   Command chains and builders for DSLs.

9. Testing

   Groovy testing with JUnit and Spock.

10. Working with Databases

    Groovy Sql API for JDBC access.

11. Differences with Java

    Semantic differences between Groovy and Java.

12. Grape Dependency Management

    Using @Grab to fetch dependencies in scripts.

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

Source: endoflife.date