Go interface composition

go-version.go

// https://play.golang.org/p/AjNOxAM4GMt

package main

import "fmt"

type I interface {
  J
  i() string
}

type J interface {
  K
  j() string
}

type K interface {
  k() string
}

type T struct {}

func (T) i() string { return "I am from I" }
func (T) j() string { return "I am from J" }
func (T) k() string { return "I am from K" }

func main() {
  var i I = T{}
  fmt.Println(i.k())
}

ruby-version.rb

class K
 def k
   "I am from K"
 end
end

class J < K
 def j
   "I am from J"
 end
end

class I < J
 def i 
   "I am from I"
 end
end

### 
# i = I.new
# i.k
# => I am from K
###