[Haskell-cafe] object oriented technique
greg at gregorycollins.net
Wed Mar 30 15:04:36 CEST 2011
On Wed, Mar 30, 2011 at 6:52 AM, Tad Doxsee <tad.doxsee at gmail.com> wrote:
> Thanks for your help. Is there any significant difference between
> using existential quantification
> data ShapeD = forall s. ShapeC => ShapeD s
> versus a GADT
> data ShapeD where
> ShapeD :: ShapeC s => s -> ShapeD
> I'm not sure I understood what you meant by "You don't need to write
> more typeclass instances this way."
Sorry, I misspoke -- they're equivalent. Personally I find the
existential easier to read.
Gregory Collins <greg at gregorycollins.net>
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