I didn't say anything when you were requesting use cases, so I have no right to complain, but I'm still a little disappointed that this doesn't fix my (admittedly very minor) issue: https://www.reddit.com/r/haskell/comments/3am0qa/existentials_and_the_heterogenous_list_fallacy/csdwlp2/?context=8&depth=9
For those who don't want to click on the reddit link: I would like to be able to write something like map show ([1, 'a', "b"] :: [forall a. Show a => a]), and have it work. On Wed, Sep 4, 2019 at 8:13 AM Alejandro Serrano Mena <trup...@gmail.com> wrote: > Hi all, > As I mentioned some time ago, we have been busy working on a new > implementation of `ImpredicativeTypes` for GHC. I am very thankful to > everybody who back then sent us examples of impredicativity which would be > nice to support, as far as we know this branch supports all of them! :) > > If you want to try it, at > https://gitlab.haskell.org/trupill/ghc/commit/a3f95a0fe0f647702fd7225fa719a8062a4cc0a5/pipelines?ref=quick-look-build > you can find the result of the pipeline, which includes builds for several > platforms (click on the "Artifacts" button, the one which looks like a > cloud, to get them). The code is being developed at > https://gitlab.haskell.org/trupill/ghc. > > Any code should run *unchanged* except for some eta-expansion required for > some specific usage patterns of higher-rank types. Please don't hesitate to > ask any questions or clarifications about it. A merge request for tracking > this can be found at > https://gitlab.haskell.org/ghc/ghc/merge_requests/1659 > > Kind regards, > Alejandro > _______________________________________________ > ghc-devs mailing list > ghc-devs@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >
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