From: bobduff@shell01.TheWorld.com   
      
   Gene  writes:   
      
   > True.   
      
   Not clear what you're replying to.   
      
   > Much nicer would be   
   >   
   > type Possibly_Valid_Float is new Float with (Unknown);   
      
   OK, but you can't expect existing code that uses Float to   
   work properly with Possibly_Valid_Floats.   
      
   Also, you can't have Possibly_Valid_Floats other than those   
   two possibilities -- it's either a Float or it's not.   
      
   You can do this sort of thing in OCaml.  Type "Maybe(Float)" is either   
   a float or nothing.  It's pretty elegant, and doesn't require any   
   special "enumeration types" or "enumeration type extensions".   
      
   - Bob   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)