Module header tidyup, phase 1

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

diff --git a/compiler/basicTypes/BasicTypes.lhs b/compiler/basicTypes/BasicTypes.lhs
index 0dbd0f6..278a284 100644 (file)
--- a/compiler/basicTypes/BasicTypes.lhs
+++ b/compiler/basicTypes/BasicTypes.lhs
@@ -1,4 +1,5 @@
 %
+% (c) The University of Glasgow 2006
 % (c) The GRASP/AQUA Project, Glasgow University, 1997-1998
 %
 \section[BasicTypes]{Miscellanous types}
@@ -38,7 +39,7 @@ module BasicTypes(
        TupCon(..), tupleParens,
 
        OccInfo(..), seqOccInfo, isFragileOcc, isOneOcc, 
-       isDeadOcc, isLoopBreaker, isNoOcc,
+       isDeadOcc, isLoopBreaker, isNonRuleLoopBreaker, isNoOcc,
 
        InsideLam, insideLam, notInsideLam,
        OneBranch, oneBranch, notOneBranch,
@@ -109,24 +110,18 @@ The @IPName@ type is here because it is used in TypeRep (i.e. very
 early in the hierarchy), but also in HsSyn.
 
 \begin{code}
-data IPName name
-  = Dupable   name     -- ?x: you can freely duplicate this implicit parameter
-  | Linear name                -- %x: you must use the splitting function to duplicate it
+newtype IPName name = IPName name      -- ?x
   deriving( Eq, Ord )  -- Ord is used in the IP name cache finite map
                        --      (used in HscTypes.OrigIParamCache)
 
-
 ipNameName :: IPName name -> name
-ipNameName (Dupable n) = n
-ipNameName (Linear  n) = n
+ipNameName (IPName n) = n
 
 mapIPName :: (a->b) -> IPName a -> IPName b
-mapIPName f (Dupable n) = Dupable (f n)
-mapIPName f (Linear  n) = Linear  (f n)
+mapIPName f (IPName n) = IPName (f n)
 
 instance Outputable name => Outputable (IPName name) where
-    ppr (Dupable n) = char '?' <> ppr n -- Ordinary implicit parameters
-    ppr (Linear  n) = char '%' <> ppr n -- Splittable implicit parameters
+    ppr (IPName n) = char '?' <> ppr n -- Ordinary implicit parameters
 \end{code}
 
 
@@ -371,18 +366,28 @@ defn of OccInfo here, safely at the bottom
 
 \begin{code}
 data OccInfo 
-  = NoOccInfo
+  = NoOccInfo          -- Many occurrences, or unknown
 
   | IAmDead            -- Marks unused variables.  Sometimes useful for
                        -- lambda and case-bound variables.
 
-  | OneOcc !InsideLam
-          !OneBranch
-          !InterestingCxt
+  | OneOcc             -- Occurs exactly once, not inside a rule
+       !InsideLam
+       !OneBranch
+       !InterestingCxt
 
   | IAmALoopBreaker    -- Used by the occurrence analyser to mark loop-breakers
                        -- in a group of recursive definitions
+       !RulesOnly      -- True <=> This loop breaker mentions the other binders
+                       --          in its recursive group only in its RULES, not
+                       --          in its rhs
+                       --  See OccurAnal Note [RulesOnly]
+
+type RulesOnly = Bool
+\end{code}
 
+
+\begin{code}
 isNoOcc :: OccInfo -> Bool
 isNoOcc NoOccInfo = True
 isNoOcc other     = False
@@ -409,8 +414,12 @@ oneBranch    = True
 notOneBranch = False
 
 isLoopBreaker :: OccInfo -> Bool
-isLoopBreaker IAmALoopBreaker = True
-isLoopBreaker other          = False
+isLoopBreaker (IAmALoopBreaker _) = True
+isLoopBreaker other              = False
+
+isNonRuleLoopBreaker :: OccInfo -> Bool
+isNonRuleLoopBreaker (IAmALoopBreaker False) = True    -- Loop-breaker that breaks a non-rule cycle
+isNonRuleLoopBreaker other                  = False
 
 isDeadOcc :: OccInfo -> Bool
 isDeadOcc IAmDead = True
@@ -427,9 +436,9 @@ isFragileOcc other      = False
 \begin{code}
 instance Outputable OccInfo where
   -- only used for debugging; never parsed.  KSW 1999-07
-  ppr NoOccInfo                                  = empty
-  ppr IAmALoopBreaker                            = ptext SLIT("LoopBreaker")
-  ppr IAmDead                                    = ptext SLIT("Dead")
+  ppr NoOccInfo           = empty
+  ppr (IAmALoopBreaker ro) = ptext SLIT("LoopBreaker") <> if ro then char '!' else empty
+  ppr IAmDead             = ptext SLIT("Dead")
   ppr (OneOcc inside_lam one_branch int_cxt)
        = ptext SLIT("Once") <> pp_lam <> pp_br <> pp_args
        where