GADTs and pedagogy was Re: GADTs and fundeps

Simon Peyton-Jones simonpj at
Thu Jul 21 07:06:27 EDT 2005

| > You mean, if the data type being defined doesn't actually use the
| > generality of GADTs, allow GADT syntax, and deriving() too?
| Yes, that would be very nice for the HaskellDemo and new users.
| I'd definitely switch all of my non-GADT datatypes to use that.

I finally got around to doing this; turned out to be trivial.

Record syntax aside, you can now declare any Haskell-98 data type using
the GADT-style where-clause syntax, including 'deriving'.


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