[GHC] #12030: GHCi Proposal: Display (Data.Kind.)Type instead of *

[GHC]

#12030: GHCi Proposal: Display (Data.Kind.)Type instead of *
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        Reporter:  Iceland_jack      |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  GHCi              |              Version:  8.1
      Resolution:                    |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by johnleo):

 Comments by Richard Eisenberg (goldfire), copied from
 [https://ghc.haskell.org/trac/ghc/ticket/12029]:

 > * `*` is not (yet) deprecated. While I did work with the larger
 community to come up with the name `Type`, I don't recall getting specific
 support for deprecating `*`. I do think this is a good direction of
 travel, but I don't think we should do this without more of a community
 mandate.
 >
 > * There are no kind synonyms in GHC 7.10 or below. Thus, according to
 the [https://prime.haskell.org/wiki/Libraries/3-Release-Policy three-
 release policy] (which isn't a formal operating policy of GHC, I don't
 think) we should wait until 8.4 before starting to deprecate `*`.
 >
 > * If the community agrees on moving away from `*`, we could add warnings
 about `*` to `-Wcompat`.
 >
 > * If the community agrees on moving away from `*`, we could also start
 changing the pretty-printer to use `Type` instead of `*`. This is not to
 be done lightly, however. There are several issues here:
 >    - Blogs, textbooks, etc., have used `*` for a long time. Furthermore,
 kinds are hard for newcomers to understand. Changing GHC's output will
 make this harder.
 >    - Until 8.4 comes out, it will be hard for a library author to
 discover that `*` is the right way to spell `Type` that is compatible with
 three releases.
 >    - The use of `*` as a kind is enshrined in the Haskell Reports. These
 Reports do not specify the error/warning behavior of a compiler, and so
 this change is not exactly a deviation from a standard. But it continues
 to make GHC seem as if it's drifting away from the standard with little
 remorse.
 >
 > * I personally think we should wait at least 5-6 years before formally
 disposing of `*`.

 I will create a proposal in [https://github.com/ghc-proposals/ghc-
 proposals] in the near future to start a conversation.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12030#comment:2>
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