Open data kinds

Jan Stolarek jan.stolarek at
Wed Dec 16 19:21:26 UTC 2015


I plan to work on implementing open data kinds (#11080). The idea is that users will be allowed to 
declare open kinds and then populate them with member types. Perhaps I will also implement closed 
data kinds. This is already possible using DataKinds, but the idea is to declare a data kind 
without corresponding data type - see #6024.

Now, consider this declaration (syntax subject to bikeshedding):

  kind K = T

In what namespace should T go: type namespace or data constructor namespace? If we put it in type 
namespace then it is possible for the user to declare a data constructor T that is completely 
unrelated to type T belonging to kind K. This might be confusing. If we put T in the data 
namespace then we miss the point of #6024.



Politechnika Łódzka
Lodz University of Technology

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