Hi all, There's been some discussion about whether to consider including GADTs in the new report, but it's been mixed up with other stuff in the thread on incorporating extensions wholesale, which has unfortunately preempted/preceded the discussion about how to go about having such discussions(!). My position on the debate is that we should avoid having the debate, just yet. (Which I intended but failed to get across in the email which unintentionally started this all off.) I think we have many much lower-hanging fruit and it'd be a better use of our time to try and get those squared away first. Doing so will help us figure out and debug the process for having such debates, which should help the GADT debate itself actually be fruitful. As well as making progress on other fronts, so we don't get mired down first thing. Whenever the debate occurs, here's a summary of the relevant emails so that they are not lost, buried in the emails of time: * Andres Löh puts forth criteria on how to judge whether extensions should be included. Mentions GADTs as an example of something that, if we decide they're a good idea in principle (criterion #1), then we should work towards things which will help them be easier to feasibly/sensibly specify (criterion #2) https://mail.haskell.org/pipermail/haskell-prime/2016-May/004104.html * wren agrees with the criteria, loves GADTs, thinks they do not fully satisfy criterion #2 https://mail.haskell.org/pipermail/haskell-prime/2016-May/004115.html * Simon Peyton Jones says type inference for GADTs has, in fact, stabilized. Albeit, not entirely satisfactory because it's "a bit operational" https://mail.haskell.org/pipermail/haskell-prime/2016-May/004119.html * Henrik Nilsson thinks GADTs are one of the most important extensions to Haskell (fwiw, wren agrees). Also worries about being able to specify type inference declaratively. https://mail.haskell.org/pipermail/haskell-prime/2016-May/004120.html * Dominique Devriese suggests including MonoLocalBinds, finds "let should not be generalized" convincing https://mail.haskell.org/pipermail/haskell-prime/2016-May/004117.html * wren finds "let should not be generalized" unconvincing https://mail.haskell.org/pipermail/haskell-prime/2016-May/004145.html -- Live well, ~wren