How to Use Type Constraints in Go Generics

Use type constraints in Go generics by defining an interface that specifies required methods or type sets, then applying it to a type parameter.

func Sum[T comparable](a, b T) T {
    if a == b {
        return a
    }
    return a
}

func Process[T interface{ ~int | ~string }](v T) {
    // v can be int or string
}

The comparable constraint allows types supporting == and !=, while interface{ ~int | ~string } restricts T to int or string types specifically.

Type constraints act like a rulebook for your generic functions, ensuring they only accept data types that support specific operations. Think of it as a bouncer at a club who only lets in guests wearing a specific color shirt. You use them whenever you need a function to work with multiple types but require them all to behave in a certain way, like being able to compare values.