Hi all,
For example, much as I love GADTs and would be all for them being added in some future language report, I do not feel they should be added this time around. (Though I emphatically and wholeheartedly support adding GADTSyntax.)
In my opinion, GADTs is one of the most important extensions of the Haskell type system over the past decade and definitely a sweet spot in the design space in terms of power vs. complexity, at least from a user perspective. I eagerly await Herbert's summary of of most used extensions (which I think will be an extremely important input when deciding how to go forward in general), but my definite impression is that GADTs (and not just GADT syntax) are used a lot. Point taken about the difficulty of specifying GADT type inference declaratively. But as long as there at least is a way to standardise inference that works, and from what Simon said there is, I do think aiming to make GADTs an official part of Haskell 2020 should be a priority. Best, /Henrik -- Henrik Nilsson School of Computer Science The University of Nottingham nhn@cs.nott.ac.uk This message and any attachment are intended solely for the addressee and may contain confidential information. If you have received this message in error, please send it back to me, and immediately delete it. Please do not use, copy or disclose the information contained in this message or in any attachment. Any views or opinions expressed by the author of this email do not necessarily reflect the views of the University of Nottingham. This message has been checked for viruses but the contents of an attachment may still contain software viruses which could damage your computer system, you are advised to perform your own checks. Email communications with the University of Nottingham may be monitored as permitted by UK legislation.