+-- selectively add ticks to interesting expressions
+addTickLHsExpr :: LHsExpr Id -> TM (LHsExpr Id)
+addTickLHsExpr (L pos e0) = do
+ e1 <- addTickHsExpr e0
+ if opt_Hpc || isGoodBreakExpr e0
+ then do
+ fn <- allocTickBox ExpBox pos
+ return $ fn $ L pos e1
+ else
+ return $ L pos e1
+
+-- general heuristic: expressions which do not denote values are good break points
+isGoodBreakExpr :: HsExpr Id -> Bool
+isGoodBreakExpr (HsApp {}) = True
+isGoodBreakExpr (OpApp {}) = True
+isGoodBreakExpr (NegApp {}) = True
+isGoodBreakExpr (HsCase {}) = True
+isGoodBreakExpr (HsIf {}) = True
+isGoodBreakExpr (RecordCon {}) = True
+isGoodBreakExpr (RecordUpd {}) = True
+isGoodBreakExpr (ArithSeq {}) = True
+isGoodBreakExpr (PArrSeq {}) = True
+isGoodBreakExpr other = False
+
+addTickLHsExprOptAlt :: Bool -> LHsExpr Id -> TM (LHsExpr Id)
+addTickLHsExprOptAlt oneOfMany (L pos e0)
+ | not opt_Hpc = addTickLHsExpr (L pos e0)
+ | otherwise = do
+ e1 <- addTickHsExpr e0
+ fn <- allocTickBox (if oneOfMany then AltBox else ExpBox) pos
+ return $ fn $ L pos e1
+