[GHC] #13341: Lift constraint products

[GHC]

#13341: Lift constraint products
-------------------------------------+-------------------------------------
        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Iceland_jack):

 The empty constraint tuple `()` becomes the unit of `:&:`

 {{{#!hs
 class    Empty a
 instance Empty a
 }}}

 `:&:` and `Empty` would presumably be added to *base*.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13341#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler