[GHC] #14880: GHC panic: updateRole

[GHC]

#14880: GHC panic: updateRole
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  goldfire
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.2.2
  checker)                           |
      Resolution:                    |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #15076            |  Differential Rev(s):  Phab:D4769
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by simonpj):

 > the "unions" approach: unions . map singleton

 That is essentially `foldr (union . singleton) empty`, which is really
 very close to `foldr insert empty`.

 What if you do a balanced tree of binary `union` operations?  I suppose
 something like
 {{{
 bigSet :: Int -> Int -> IntSet
 bigSet m n
   | m==n = singleton n
   | otherwise = bigSet m mid `union` bigSet (mid+1) n
   where
     mid = (n+m)/2
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14880#comment:58>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler