Proposal: Introducing Concepts Instead of typename

[Apricot-S]

Description

The top-level CMakeLists.txt specifies set(CMAKE_CXX_STANDARD 23), which means the project already requires C++23.
Given this, I would like to propose replacing unconstrained typename parameters with C++20/23 concepts where appropriate.

Motivation

• Leverage modern C++: Since the project already targets C++23, we can safely use concepts without worrying about compatibility.
• Improved readability: Concepts make template constraints explicit, helping users understand the intended usage more quickly.
• Better diagnostics: Concepts provide clearer compiler error messages compared to unconstrained typename.

Example

// Current
template<typename ForwardRange>
std::uint_fast8_t calculateReplacementNumber(ForwardRange const &r);

// Proposed with concepts
template<std::ranges::forward_range ForwardRange>
std::uint_fast8_t calculateReplacementNumber(ForwardRange const &r);

Reference branch

For clarity, I have prepared a forked branch that demonstrates this idea:
https://github.com/Apricot-S/nyanten/tree/feat/concepts

Benefits

• Makes the codebase more self-documenting.
• Provides stronger guarantees about template usage.