[GHC] #10980: Deriving Read instance from datatype with N fields leads to N^2 code size growth

[GHC]

#10980: Deriving Read instance from datatype with N fields leads to N^2 code size
growth
-------------------------------------+-------------------------------------
        Reporter:  slyfox            |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.2
      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 simonpj):

 Reid, interesting!  So you think it's all in the code generation and
 closure construction.

 Can you give a simple test case, separate from `deriving Read` that
 demonstrates the phenomenon, with the monadic and applicative versions
 side by side, but with very different perf?  That would help to focus our
 attention.

 Thanks

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10980#comment:8>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler