[GHC] #7206: Implement cheap build

[GHC]

#7206: Implement cheap build
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              Reporter:  simonpj     |            Owner:  simonpj
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:  ⊥
             Component:  Compiler    |          Version:  7.4.2
            Resolution:              |         Keywords:
      Operating System:              |     Architecture:  Unknown/Multiple
  Unknown/Multiple                   |       Difficulty:  Unknown
       Type of failure:              |       Blocked By:
  None/Unknown                       |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by dfeuer):

 Even more kinds of producers makes for even more fusion rules. If we
 decide to rewrite ''all'' consumers to `foldr`, I suppose that then opens
 up the possibility of having multiple producers instead, but expanding on
 both ends makes for a rule explosion. I'm also trying, on and off, to see
 if we can get away with writing all these enumerations using `unfoldr` or
 similar; I'm not sure how these ideas interact.

 An idea that might be crazy: introduce a local annotation indicating that
 a certain function should be treated as `CONLIKE` at a particular call
 site. So then you'd have just `{-# CHEAP #-} build blah` and leave the
 fusion rules alone.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7206#comment:7>
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