X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FbasicTypes%2FBasicTypes.lhs;h=820a3b95754e06ce00d450a374ffe25d4538959a;hb=bca9dd54c2b39638cb4638aaccf6015a104a1df5;hp=47ad787842111e6edc32896904857930ae15d4ff;hpb=111cee3f1ad93816cb828e38b38521d85c3bcebb;p=ghc-hetmet.git

diff --git a/ghc/compiler/basicTypes/BasicTypes.lhs b/ghc/compiler/basicTypes/BasicTypes.lhs
index 47ad787..820a3b9 100644
--- a/ghc/compiler/basicTypes/BasicTypes.lhs
+++ b/ghc/compiler/basicTypes/BasicTypes.lhs
@@ -14,7 +14,7 @@ types that
 
 \begin{code}
 module BasicTypes(
-	Version,
+	Version, bumpVersion, initialVersion, bogusVersion,
 
 	Arity, 
 
@@ -29,10 +29,14 @@ module BasicTypes(
 
 	TopLevelFlag(..), isTopLevel, isNotTopLevel,
 
-	OccInfo(..), seqOccInfo, isFragileOccInfo,
+	Boxity(..), isBoxed, tupleParens,
+
+	OccInfo(..), seqOccInfo, isFragileOcc, isDeadOcc, isLoopBreaker,
+
 	InsideLam, insideLam, notInsideLam,
-	OneBranch, oneBranch, notOneBranch
+	OneBranch, oneBranch, notOneBranch,
 
+        EP(..)
    ) where
 
 #include "HsVersions.h"
@@ -75,6 +79,17 @@ type Arity = Int
 
 \begin{code}
 type Version = Int
+
+bogusVersion :: Version	-- Shouldn't look at these
+bogusVersion = error "bogusVersion"
+
+bumpVersion :: Bool -> Version -> Version 
+-- Bump if the predicate (typically equality between old and new) is false
+bumpVersion False v = v+1
+bumpVersion True  v = v
+
+initialVersion :: Version
+initialVersion = 1
 \end{code}
 
 
@@ -121,7 +136,6 @@ negatePrecedence = 6
 data NewOrData
   = NewType  	-- "newtype Blah ..."
   | DataType 	-- "data Blah ..."
-  | EnumType	-- Enumeration; all constructors are nullary
   deriving( Eq )	-- Needed because Demand derives Eq
 \end{code}
 
@@ -147,6 +161,28 @@ isTopLevel NotTopLevel  = False
 
 %************************************************************************
 %*									*
+\subsection[Top-level/local]{Top-level/not-top level flag}
+%*									*
+%************************************************************************
+
+\begin{code}
+data Boxity
+  = Boxed
+  | Unboxed
+  deriving( Eq )
+
+isBoxed :: Boxity -> Bool
+isBoxed Boxed   = True
+isBoxed Unboxed = False
+
+tupleParens :: Boxity -> SDoc -> SDoc
+tupleParens Boxed   p = parens p
+tupleParens Unboxed p = ptext SLIT("(#") <+> p <+> ptext SLIT("#)")
+\end{code}
+
+
+%************************************************************************
+%*									*
 \subsection[Recursive/Non-Recursive]{Recursive/Non-Recursive flag}
 %*									*
 %************************************************************************
@@ -164,6 +200,42 @@ isNonRec Recursive    = False
 isNonRec NonRecursive = True
 \end{code}
 
+%************************************************************************
+%*									*
+\subsection[Generic]{Generic flag}
+%*									*
+%************************************************************************
+
+This is the "Embedding-Projection pair" datatype, it contains 
+two pieces of code (normally either RenamedHsExpr's or Id's)
+If we have a such a pair (EP from to), the idea is that 'from' and 'to'
+represents functions of type 
+
+	from :: T -> Tring
+	to   :: Tring -> T
+
+And we should have 
+
+	to (from x) = x
+
+T and Tring are arbitrary, but typically T is the 'main' type while
+Tring is the 'representation' type.  (This just helps us remember 
+whether to use 'from' or 'to'.
+
+\begin{code}
+data EP a = EP { fromEP :: a,	-- :: T -> Tring
+		 toEP   :: a }	-- :: Tring -> T
+\end{code}
+
+Embedding-projection pairs are used in several places:
+
+First of all, each type constructor has an EP associated with it, the
+code in EP converts (datatype T) from T to Tring and back again.
+
+Secondly, when we are filling in Generic methods (in the typechecker, 
+tcMethodBinds), we are constructing bimaps by induction on the structure
+of the type of the method signature.
+
 
 %************************************************************************
 %*									*
@@ -205,9 +277,17 @@ type OneBranch = Bool	-- True <=> Occurs in only one case branch
 oneBranch    = True
 notOneBranch = False
 
-isFragileOccInfo :: OccInfo -> Bool
-isFragileOccInfo (OneOcc _ _) = True
-isFragileOccInfo other	      = False
+isLoopBreaker :: OccInfo -> Bool
+isLoopBreaker IAmALoopBreaker = True
+isLoopBreaker other	      = False
+
+isDeadOcc :: OccInfo -> Bool
+isDeadOcc IAmDead = True
+isDeadOcc other	  = False
+
+isFragileOcc :: OccInfo -> Bool
+isFragileOcc (OneOcc _ _) = True
+isFragileOcc other	      = False
 \end{code}
 
 \begin{code}