[GHC] #14164: GHC hangs on type family dependency

[GHC]

#14164: GHC hangs on type family dependency
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  merge
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:
                                     |  InjectiveFamilies
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:  indexed-
                                     |  types/should_compile/T14164
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 Can you give an example?

 One thing to remember: normal substitution is (carefully designed to be)
 one-shot.  That is, it's fine to substitute `a :-> [a]`, say.  Even if
 they happen to have the same unique, we think of the range and the domain
 as coming from different address spaces.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14164#comment:9>
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