What are parametric types in Julia and how do they improve performance?

Parametric types allow type definitions with type parameters, enabling specialization and zero-cost abstractions.

Parametric types let developers define generic structures that are specialized at compile time. For example, Vector{T} creates a distinct type for each element type. This allows Julia to generate optimized code for each specialization, eliminating runtime type checks. It is a key mechanism behind Julia’s performance model and type inference system.