Hi Janek, Shouldn't it be represented the same way as in GHC's own AST? Especially regarding a recent thread about unifying the two (IIRC). On 12/21/2015 07:52 PM, Jan Stolarek wrote:
GHC Users,
I am working on adding proper support for GADTs in Template Haskell. By proper I mean that GADTs data constructors will no longer be encoded using H98 data constructors, but will be represented explicity.
GADTs allow to declare several constructors with the same signature:
data T where MkT1, MkT2 :: T
The question is whether to represent such constructors in TH syntax as:
(1) GadtC [Name] [StrictType] Name [Type] -- or: (2) GadtC Name [StrictType] Name [Type]
Note the difference in first field. (1) is closer to the original syntax, as it stores the list of all names in a single declaration, as was originally written in the source code. (2) requires to have a separate `GadtC` for each constructor even if constructors were declared together, as in the example above.
I would like to hear from TH users which of these two representations you prefer. At the moment I have implemented (1) as it directly represents source syntax. The downside of (1) is that information whether several data constructors were declared together is not recoverable during reification, and so reifying T will yield:
data T where MkT1 :: T MkT2 :: T
Janek
--- Politechnika Łódzka Lodz University of Technology
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