Are there GHC extensions we'd like to incorporate wholesale?

[Henrik Nilsson]

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 at cs.nott.ac.uk




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