change the TcM monad to continuation passing style. The old monad caused stack overflow for large search spaces

1 files changed, 4 insertions, 4 deletions

diff --git a/src/runtime/haskell/PGF/Forest.hs b/src/runtime/haskell/PGF/Forest.hs
index 5d06f4e97..a4a9266f7 100644
--- a/src/runtime/haskell/PGF/Forest.hs
+++ b/src/runtime/haskell/PGF/Forest.hs
@@ -119,7 +119,7 @@ isLindefCId id
 getAbsTrees :: Forest -> PArg -> Maybe Type -> Maybe Int -> Either [(FId,TcError)] [Expr]

 getAbsTrees (Forest abs cnc forest root) arg@(PArg _ fid) ty dp =

   let (err,res) = runTcM abs (do e <- go Set.empty emptyScope (fmap (TTyp []) ty) arg

-                                 generateForForest (prove dp) e) fid IntMap.empty

+                                 generateForForest (prove dp) e) emptyMetaStore fid

   in if null res

        then Left  (nub err)

        else Right (nubsort [e | (_,_,e) <- res])

@@ -205,7 +205,7 @@ instance Selector FId where
   splitSelector s = (s,s)

   select cat scope dp = do

     gens <- typeGenerators scope cat

-    TcM (\abstr s ms -> iter s ms gens)

+    TcM (\abstr k h -> iter k gens)

     where

-      iter s ms []              = Zero

-      iter s ms ((_,e,tty):fns) = Plus (Ok s ms (e,tty)) (iter s ms fns)

+      iter k []              ms s = id

+      iter k ((_,e,tty):fns) ms s = k (e,tty) ms s . iter k fns ms s