Interface Inheritance in p6i

• A subinterface may add method signatures.

  bbuf_peeki = class implements bbuf_peek extends bbuf_basei
    peek = method({full,mid}b:self{-}) replies(int) 
      reply(b.arr[b.opt])
    end peek
  end bbuf_basei
  

• A subinterface may split some states.

  bbuf_hl = interface { empty, low, high, full }
      extends bbuf { mid } becomes { low, high }
    putlow = method({empty,low}b:self{empty,low,high})
  end bbuf_hl
  

• A subinterface may remove some states. (!!!)

  bbuf_u = interface { empty, mid }
      extends bbuf { full } removed
  end bbuf_u