Are anonymous type classes the right model at all? (replying to Re: Are fundeps the right model at all?)

Tom Pledger [email protected]
Tue, 9 Jan 2001 10:30:52 +1300


Marcin 'Qrczak' Kowalczyk writes:
 [...]
 > My new record scheme proposal does not provide such lightweight
 > extensibility, but fields can be added and deleted in a controlled
 > way if the right types and instances are made.

Johan Nordlander must be on holiday or something, so I'll deputise for
him.   :-)

O'Haskell also has add-a-field subtyping.  Here's the coloured point
example (from http://www.cs.chalmers.se/~nordland/ohaskell/survey.html):

   struct Point =
      x,y :: Float

   struct CPoint < Point =
      color :: Color

Regards,
Tom