[GHC] #8041: Extraction of Uniques is in some places done inefficiently

[GHC]

#8041: Extraction of Uniques is in some places done inefficiently
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       Reporter:  parcs             |             Owner:
           Type:  bug               |            Status:  new
       Priority:  normal            |         Milestone:
      Component:  Compiler          |           Version:  7.6.3
       Keywords:                    |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 In some places in the GHC sources, extraction of a `Unique` from a
 `UniqSupply` is done in the following manner:

 {{{
 case splitUniqSupply us of
     (us1,us2) -> (uniqFromSupply us1, us2)
 }}}

 This way of splitting a `UniqSupply` into a `Unique` and a new
 `UniqueSupply` is needlessly inefficient since it forces and then throws
 away an extra `Unique`.

 `takeUniqFromSupply` should be used instead.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8041>
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