Functional algorithm implementations in Hy

Create purely functional implementations of common algorithms in Hy:

## Functional programming patterns:
- Recursive implementations
- Higher-order functions
- Immutable data structures
- Function composition
- Currying and partial application

## Functional algorithms to implement:
- Functional sorting algorithms
- Functional tree traversals
- Functional graph algorithms
- Map-filter-reduce patterns
- Functional data structure operations

## Educational components:
- Contrast with imperative implementations
- Performance comparisons
- Memory usage analysis
- Recursion vs. iteration trade-offs

## Requirements:
- Use pure functions without side effects
- Employ Hy's functional programming features
- Create comprehensive test cases
- Document functional programming patterns

This collection will leverage Hy's Lisp-like functional programming capabilities to demonstrate elegant, concise implementations of algorithms that highlight the functional programming paradigm.