[GHC] #9499: Add -prelude-is flag

[GHC]

#9499: Add -prelude-is flag
-------------------------------------+-------------------------------------
        Reporter:  agibiansky        |                   Owner:  agibiansky
            Type:  feature request   |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.9
      Resolution:                    |                Keywords:  flag
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:  #9590             |                Blocking:
                                     |  Differential Revisions:  Phab:D171
-------------------------------------+-------------------------------------
Changes (by hvr):

 * related:   => #9590


Comment:

 Tbh, I wouldn't like seeing the `ghc-options: -is-prelude foobar` approach
 spread, as it would be a rather adhoc GHC-specific hack IMO, and also
 require `if impl(ghc >= ...)` guards if older GHCs are to be supported

 Moreover, I don't understand why the current implicit `Prelude` approach
 requires "having to import an alternative prelude everywhere", and how
 `-is-prelude` would help here. (I'd also like to point to
 comment:ticket:9590:20)

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9499#comment:7>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler