dot_product.go

package main

func main() {
	v3 := Vector3D[int]{1,2,3}
	println(DProd[Vector3D[int], int](v3,v3))
}

type Numeric interface {
	~int | ~int8 | ~int16 | ~int32 | ~int64 |
	~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr |
	~float32 | ~float64 |
	~complex64 | ~complex128
}

type Vector2D[T Numeric] [2]T
type Vector3D[T Numeric] [3]T

func (v Vector2D[T]) DProd(w Vector2D[T]) T {
	var result T
	for i:=range v { result += v[i]*w[i] }
	return result
}

func (v Vector3D[T]) DProd(w Vector3D[T]) T {
	var result T
	for i:=range v { result += v[i]*w[i] }
	return result
}

// 言語仕様に次のようにあるので、 TのスコープはDProdの直後から始まり、 V interface{DProd(V) T}のようにTを参照できる
// 
// The scope of an identifier denoting a type parameter of a parameterized function
//	    or declared by a method Receiver begins after the function name
//	    and ends at the end of the function body. 
func DProd[V interface{DProd(V) T}, T Numeric](v, w V) T {
	return v.DProd(w)
}