… add notes

The project now uses direnv to manage the development environment.  A `.envrc` file has been added to configure environment variables and manage dependencies.  The `.gitignore` file has been updated to ignore direnv and other development-related files.  Notes on functional programming in Java and JVM troubleshooting have been added to `Notes.md`. The Java version has been upgraded to 21.  A `devenv.nix` file has been added to manage the Nix development environment.  A `devenv.yaml` file has been added to configure the development environment.  The `functional_programming_in_java.pdf` file has been added.  The `build.gradle` file has been updated to use Java 21.

The commit adds a section to the Notes.md file detailing the steps for setting up a Nix-based development environment.  This improves reproducibility and consistency across different development machines.

This commit introduces a new script, `watch-pull.sh`, that
automates the process of periodically pulling changes from a
selected remote branch.  The script uses `fzf` for
interactive branch selection and allows the user to specify
the update interval.  This improves developer workflow by
providing a convenient way to monitor and update specific
remote branches.

The commit adds several sections to the Notes.md file:

- AI Assist: Links to Google's Gemini Code Assist documentation.
- In Bits and Bytes: A table summarizing the sizes of common data types in Java.
- Latency Numbers Every Programmer Should Know: A table listing latency numbers for various operations.
- Powers of 10 (Time Units) and Powers of 2 (Common Data Units): Tables summarizing common time and data units and their abbreviations.
- Decimal vs Binary Prefixes: A table comparing decimal and binary prefixes and highlighting the percentage difference.

These additions provide valuable reference information for future learning and development.

…eSupplier functional interfaces

The commit adds several new test cases demonstrating the use of `Supplier` and `DoubleSupplier` functional interfaces with lambda expressions and method references.  This enhances the test suite's coverage of functional programming concepts in Java.

…xpressions

The `CurryingExample.java` file demonstrates the concept of currying in Java using lambda expressions.  It shows how to define a curried function, apply arguments one by one, and perform partial application to create specialized functions.  This example enhances understanding of functional programming concepts.

…urrying example code formatting

The `Notes.md` file has been updated to include notes on Vavr.io, a functional programming library for Java.  The `CurryingExample.java` file's code formatting has been improved for better readability, making the curried function definition clearer.

- Consolidated static imports for assertions
- Implemented missing TODOs with directory filters using lambdas, anonymous inner class, and block lambdas
- Added assertions for directories count where applicable
- Minor improvements to test logging with `System.out.println`

…rExercises`

- Replaced commented-out TODOs with proper implementations in `LazyEvaluationExercises`
- Added filename and directory filters using lambdas and method references in `FileFilterExercises`
- Included assertions for file/directory counts and .java extensions

- Add `@SuppressWarnings("Convert2MethodRef")` to avoid inspection noise
- Replace `collect(Collectors.toList())` with `.toList()`
- Adjust regex in `split` method for consistency with whitespace handling
- Simplify `LinkedList` instantiation using diamond operator
- Use `parallelStream` for potential performance improvements

- Use `isEmpty()` instead of `size() == 0` in `FlatMapDemo`
- Migrate `CompanyEmployee` to a `record` for brevity and immutability
- Adjust `Employee` interface methods to align with record fields
- Add `mapForEach` test method in `FileFilterExercises` to explore map iteration techniques
- Update `CompanyEmployeeTest` to test the new record structure

- Implemented various scenarios for `reduce`, such as summing numbers, string concatenation, counting characters, and filtering with reduction
- Included tests for `IntStream.sum()` and optional handling with `orElse`

Added a new image file, `haskell_gaming.png`, likely for use as a logo or graphic within the project.  This enhances the project's visual appeal or provides necessary assets.

✨ (Notes.md): Add new sections on JSpecify, OCaml, and Haskell

✨ (Notes.md): Add a new section on Streams, detailing types of operations and their purposes.

✨ (img.png): Add image for Haskell gaming section

The commit adds several new links to resources related to Java, functional programming, and other programming languages.  It also introduces new sections on JSpecify, OCaml, Haskell, and Streams, providing more detailed information and examples.  Finally, an image related to Haskell gaming is added to enhance the notes.