[Enhancement] Tuple type support

[yhk1038]

Overview

A feature proposal to add Tuple type support to T-Ruby.

A tuple is an array-like type with a fixed length where each position can have a different type. Implementing this with TypeScript-like syntax would significantly enhance T-Ruby's type expressiveness.

Proposed Syntax

# Basic tuple type
def get_user_info: [String, Integer]
  ["Alice", 25]
end

# Rest elements
def get_values: [String, *Integer]
  ["header", 1, 2, 3]
end

# Optional elements
def parse_result: [Boolean, String?]
  [true, nil]
end

Use Cases

1. Multiple return values: Explicitly specify types for each value when returning multiple values from a function
2. Structured data: Represent fixed structures like CSV rows, coordinates, key-value pairs
3. Pattern matching: Combine with Ruby 3.0+ pattern matching for type-safe destructuring

References

• TypeScript Tuple Types
• RBS Tuple Type