Monomorphization

Monomorphization in Rust

Process in Rust compiler (rustc) that converts generic code (e.g., using <T>) into type-specific (monomorphic) code at compile time.

• Purpose: Ensures type-safe, optimized machine code with no runtime overhead for generics.
• How It Works:
  • Generic functions/types are replaced with concrete versions for each used type.
  • Example: fn foo<T>(x: T) called with i32 and f64 generates foo_i32 and foo_f64.
• Pros:
  • Fast execution (no runtime type resolution).
  • Type safety guaranteed at compile time.
• Cons:
  • Increases compile time.
  • Larger binary size if many types are used.
• Context: Handled by rustc_monomorphize module in Rust compiler.
• Example:

    fn add<T: std::ops::Add<Output = T>>(a: T, b: T) -> T { a + b }
    // Compiler generates add_i32, add_f64, etc., for each type used.
    ```