generics.go

package main

import (
  "fmt"
)

func double[T int | float64](x T) T {
  return T(2) * x
}

func main() {
  var a int = 5
  var adbl = double(a)
  var b float64 = 5.5
  var bdbl = double(b)
  fmt.Printf("adbl = %d, bdbl = %f\n", adbl, bdbl)
}

tobi@ark:~/tmp> go version
go version go1.18rc1 linux/amd64
tobi@ark:~/tmp> ./generics 
adbl = 10, bdbl = 11.000000