[GHC] #8957: ghci's :l -> internal error: evacuate: strange closure type 8306

4 Apr 2014

      #8957: ghci's :l -> internal error: evacuate: strange closure type 8306
----------------------------------+-------------------------------
       Reporter:  guest           |             Owner:
           Type:  bug             |            Status:  new
       Priority:  normal          |         Milestone:
      Component:  GHCi            |           Version:  7.6.3
       Keywords:                  |  Operating System:  Windows
   Architecture:  x86_64 (amd64)  |   Type of failure:  GHCi crash
     Difficulty:  Unknown         |         Test Case:
     Blocked By:                  |          Blocking:
Related Tickets:                  |
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 GHCi crashes when :loading a file. Unfortunately I can't reproduce the
 bug, so this one's gonna be lots of information that probably will help
 very little.

 This is the actual error message:

 {{{
 *CommonStatistics Data.List> :l SimpleCellularALife
 [1 of 2] Compiling CommonStatistics ( CommonStatistics.hs, interpreted )
 <interactive>: internal error: evacuate: strange closure type 8306
     (GHC version 7.6.3 for i386_unknown_mingw32)
     Please report this as a GHC bug:
 http://www.haskell.org/ghc/reportabug

 This application has requested the Runtime to terminate it in an unusual
 way.
 Please contact the application's support team for more information.
 }}}

 This one was the error I was working on, i.e. the (legit) error in the
 previous call: (Including this because it gives you a clue what I was
 working on, I was mostly fiddling around with parens in placeAgents' gnd
 function)

 {{{
 *CommonStatistics Data.List> :l SimpleCellularALife
 [1 of 2] Compiling CommonStatistics ( CommonStatistics.hs, interpreted )
 [2 of 2] Compiling SimpleCellularALife ( SimpleCellularALife.hs,
 interpreted )

 SimpleCellularALife.hs:70:28:
     Couldn't match expected type `Array i0 e0'
                 with actual type `Ground'
     In the return type of a call of `ground'
     In the first argument of `(!)', namely `ground (tiles w)'
     In the expression: (ground (tiles w) ! (fst $ head grp))

 SimpleCellularALife.hs:70:36:
     Couldn't match expected type `Tile'
                 with actual type `Array Coordinates Tile'
     In the return type of a call of `tiles'
     In the first argument of `ground', namely `(tiles w)'
     In the first argument of `(!)', namely `ground (tiles w)'
 Failed, modules loaded: CommonStatistics.
 }}}

 Included Source Files - CommonStatistics.hs:
 {{{
 module CommonStatistics where

 type Memory = [Int]--Internal state of an Agent.

 data StatUpdate = StatUpdate{
         newVictories :: [Int] -- by agentID
 } deriving (Show)

 data Agent = Agent{
         agentID :: Int,

         sourcePath :: FilePath, --path to .hs source file. relative to
 executable

         doFunc :: [String] -> Memory -> (Memory, [String]),

         evFunc :: [String] -> Memory -> (Memory, String),

         personalMemory :: Memory
 }

 instance Show Agent where
         show (Agent {
                 agentID = aID,
                 sourcePath = path,
                 doFunc = forgetit,
                 evFunc = forgetittoo,
                 personalMemory = mem
         }) = show (aID, path, mem)
 }}}

 And SimpleCellularALife.hs: (I am not exactly confident that this is the
 version that caused the error. I sadly can't reproduce it, so there's no
 confirming that.

 {{{
 module SimpleCellularALife where

 import Data.Array
 import Data.List
 import System.Random
 import CommonStatistics

 data Ground = Ground {
         food :: Int
 }

 data Entity = Entity{
         ai :: Agent,
         health :: Int
 }

 data Tile = Tile{
         ground :: Ground,
         entities :: [Entity]
 }

 data World = World {
         tiles :: Array Coordinates Tile
 }

 type Coordinates = (Int, Int)

 getRandomPosition :: RandomGen t => World -> t -> (t, Coordinates)
 getRandomPosition w rand =
         let
                 ((minx, miny), (maxx, maxy)) = bounds $ tiles w
                 (x, rand2) = randomR (minx, maxx) rand
                 (y, rand3) = randomR (miny, maxy) rand2
         in
                 (rand3, (x, y))

 placeAgents :: RandomGen t => World -> [Agent] -> t -> (t, World)
 placeAgents w agents rand =
         let
                 createTileUpdates (ag:ags) wrld rnd =
                         let
                                 (rnd2, coords) = getRandomPosition wrld
 rnd
                                 (rnd3, restUpd) = createTileUpdates ags
 wrld rnd2
                         in (rnd3, (coords, ag) : restUpd)
                 createTileUpdates [] wrld rnd = (rnd, [])

                 (rand2, assocList) = createTileUpdates agents w rand
                 groupedAssocList = groupBy (\(c1, a1) (c2, a2) -> c1 ==
 c2) $ sortBy (\(c1, a1) (c2, a2) -> compare c1 c2) assocList
                 gnd grp = ground ((tiles w) ! (fst $ head grp))
                 condenseGroup grp = (fst $ head grp, Tile{ground = gnd
 grp, entities = snd $ unzip grp})
                 --map condenseGroup groupedAssocList --::(Coordinates,
 Tile)

         in
                 (rand, w)
                 --placeAgents (placeAgent w firstAg x y) agents rand3
 }}}

 Someone suggested that this might've been GHCI running out of memory. I am
 as of writing this at 66% out of 4GB used. The GHCI instance was opened
 for an extended period of time, so it might have racked up quite a bit of
 RAM usage. I can say though that considering the file sizes, 1.3GB of RAM
 usage seems unreasonable.

 And because I haven't yet written enough, here are all the variations of
 the line I was working on that could've caused it. Pulled them out of my
 text editor's buffer.

 {{{
 gnd grp = (ground (tiles w) ! fst $ head grp)
 gnd grp = (ground (tiles w) ! (fst $ head grp)
 gnd grp = (ground (tiles w) ! (fst $ head grp))
 gnd grp = (ground ((tiles w) ! (fst $ head grp))
 gnd grp = ground ((tiles w) ! (fst $ head grp))
 }}}

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8957
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