[GHC] #9637: Type level programming needs an error function

[GHC]

#9637: Type level programming needs an error function
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        Reporter:  augustss          |                Owner:
            Type:  feature request   |               Status:  closed
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.8.3
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #9180, #9636      |  Differential Rev(s):  Phab:D1236
       Wiki Page:                    |
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Comment (by bgamari):

 I embellished the documentation a bit in
 568736d757d3e0883b0250e0b948aeed646c20b5.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9637#comment:13>
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