Make recursion and RULES interact better

[ghc-hetmet.git] / compiler / basicTypes / BasicTypes.lhs

diff --git a/compiler/basicTypes/BasicTypes.lhs b/compiler/basicTypes/BasicTypes.lhs
index d73e4f1..e6e3a90 100644 (file)
--- a/compiler/basicTypes/BasicTypes.lhs
+++ b/compiler/basicTypes/BasicTypes.lhs
@@ -365,12 +365,14 @@ defn of OccInfo here, safely at the bottom
 
 \begin{code}
 data OccInfo 
-  = NoOccInfo
+  = NoOccInfo          -- Many occurrences, or unknown
+
+  | RulesOnly          -- Occurs only in the RHS of one or more rules
 
   | IAmDead            -- Marks unused variables.  Sometimes useful for
                        -- lambda and case-bound variables.
 
-  | OneOcc !InsideLam
+  | OneOcc !InsideLam  -- Occurs exactly once, not inside a rule
           !OneBranch
           !InterestingCxt
 
@@ -422,6 +424,7 @@ isFragileOcc other      = False
 instance Outputable OccInfo where
   -- only used for debugging; never parsed.  KSW 1999-07
   ppr NoOccInfo                                  = empty
+  ppr RulesOnly                                  = ptext SLIT("RulesOnly")
   ppr IAmALoopBreaker                            = ptext SLIT("LoopBreaker")
   ppr IAmDead                                    = ptext SLIT("Dead")
   ppr (OneOcc inside_lam one_branch int_cxt)