[GHC] #9086: main :: IO Int does different things with runghc and when compiled

[GHC]

#9086: main :: IO Int does different things with runghc and when compiled
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       Reporter:  nh2     |             Owner:
           Type:  bug     |            Status:  new
       Priority:  normal  |         Milestone:  7.10.1
      Component:          |           Version:  7.8.2
  Compiler                |  Operating System:  Unknown/Multiple
       Keywords:          |   Type of failure:  Incorrect result at runtime
   Architecture:          |         Test Case:
  Unknown/Multiple        |          Blocking:
     Difficulty:          |
  Unknown                 |
     Blocked By:          |
Related Tickets:          |
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 Consider

 {{{
 main :: IO Int
 main = return 1
 }}}

 This does different things when compiled and when run with
 `runghc`/`runhaskell` (it prints an extra `1` with the latter).

 For practical purposes, I think it is beneficial if either of the two ways
 to run a Haskell program have the same output.

 Or did somebody intend this to happen?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9086>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler