Generics vs Interfaces in Go

Use interfaces to define behavior contracts for polymorphism and generics to create reusable data structures that work with multiple types. Interfaces describe what a type can do, while generics describe how to handle data of specific types without losing type safety.

// Interface: Defines behavior (what it does)
type Reader interface {
    Read(p []byte) (n int, err error)
}

// Generic: Defines reusable structure (how it stores data)
type Stack[T any] struct {
    items []T
}

func (s *Stack[T]) Push(item T) {
    s.items = append(s.items, item)
}

Think of an interface as a job description that any employee can fill as long as they can perform the required tasks. A generic is like a reusable box template that you can resize to hold different items without changing the box's design. Use interfaces when you care about actions, and generics when you care about the data structure itself.