[GHC] #13408: Consider inferring a higher-rank kind for type synonyms

[GHC]

#13408: Consider inferring a higher-rank kind for type synonyms
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        Reporter:  goldfire          |                Owner:  (none)
            Type:  feature request   |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:  wontfix           |             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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Changes (by goldfire):

 * status:  new => closed
 * resolution:   => wontfix


Comment:

 Actually, this is all bogus. In `type G = F`, `F` is undersaturated, which
 is disallowed. And once we write `type G z = F z`, when we're inferring a
 higher-rank type for `z`, we've gone further off the map than I'm
 comfortable with.

 Additionally, getting this right would require tracking recursiveness in
 type declarations more than we do already, and it's not worth the pain.

 So I'm closing as wontfix. Anyone who wants this can always add a kind
 signature.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13408#comment:2>
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