Fix Trac 1865: GHCi debugger crashes with :print

[ghc-hetmet.git] / compiler / main / InteractiveEval.hs

diff --git a/compiler/main/InteractiveEval.hs b/compiler/main/InteractiveEval.hs
index bfcf5f6..bf7c7b4 100644 (file)
--- a/compiler/main/InteractiveEval.hs
+++ b/compiler/main/InteractiveEval.hs
@@ -441,7 +441,6 @@ resume (Session ref) step
                         handleRunStatus expr ref bindings final_ids
                                         breakMVar statusMVar status hist'
 
-
 back :: Session -> IO ([Name], Int, SrcSpan)
 back  = moveHist (+1)
 
@@ -610,7 +609,7 @@ rttiEnvironment hsc_env@HscEnv{hsc_IC=ic} = do
    let substs = [computeRTTIsubst ty ty' 
                  | (ty, Just ty') <- zip (map idType incompletelyTypedIds) tys]
        ic'    = foldr (flip substInteractiveContext) ic 
-                           (map skolemiseSubst $ catMaybes substs)
+                           (map skolemiseSubst substs)
    return hsc_env{hsc_IC=ic'}
 
 skolemiseSubst subst = subst `setTvSubstEnv`