Sample Generic Summer

generics.go

package main

import "fmt"

type Number interface {
	type int, float32
}

func sum[T any, V Number](items []T, getvalue func(T) V) V {
   var acc V

   for _, item := range items {
      acc += getvalue(item)
   }

   return acc;
}

type Payment = struct{
   Id string
   Amount int
   Gross float32
}


func main() {
    payments := []Payment{
       { "one", 1, 11 },
       { "two", 2, 22 },
       { "three", 3, 33 },
    }

    fmt.Println("Amount", sum(payments, func (item Payment) int { return item.Amount }))
    fmt.Println("Gross", sum(payments, func (item Payment) float32 { return item.Gross }))
}