mutually recursive interfaces and enums for types

relsAndRelTypes.java

interface reltype<t extends Enum<t> & reltype<t,r>, r extends rel<r,t>> {

  public t value();
}

interface rel<r extends rel<r,t>, t extends Enum<t> & reltype<t,r>> {

  public t getType();
}


// use it
interface Knows extends rel<Knows, KNOWS> {

  public KNOWS getType();
}

enum KNOWS implements reltype<TaxonRelType, TaxonRel> { 
  
  INSTANCE; public KNOWS value() { return INSTANCE; } 
}