[GHC] #14180: Strange/bad error message binding unboxed type variable

[GHC]

#14180: Strange/bad error message binding unboxed type variable
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        Reporter:  dfeuer            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.2.3
       Component:  Compiler (Type    |              Version:  8.3
  checker)                           |
      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 RyanGlScott):

 Replying to [comment:7 simonpj]:
 > But do you really want unboxed types in kinds??

 ...Yes? I mean, that's what dfeuer was presumably trying to do in the
 original program. But moreover, I find it rather strange that the typing
 rule for `(->)` is less general in kinds than it is in types.

 I don't care so much about removing the `TypeLevel`/`KindLevel`
 distinction, especially if keeping it will improve error message quality
 elsewhere. But I do think that we shouldn't check for this distinction in
 `tc_fun_type`.

 ...However, it should be noted that I tried implementing that
 `tc_fun_type` suggestion, but even still that doesn't make the original
 program (the `MatchInt` one) typecheck, so I guess my hunch was misplaced.
 For some reason, GHC expects the type of all type variables to have kind
 `Type` (as opposed to how things work on the value level, where they can
 have kind `TYPE r` for some `RuntimeRep` `r`). I'm not sure where that is
 decided, but it's not `tc_fun_type` it seems.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14180#comment:8>
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