\begin{code}
module BasicTypes(
- Version, Arity,
+ Version, bumpVersion, initialVersion, bogusVersion,
+
+ Arity,
+
Unused, unused,
+
Fixity(..), FixityDirection(..),
defaultFixity, maxPrecedence, negateFixity, negatePrecedence,
+
NewOrData(..),
+
RecFlag(..), isRec, isNonRec,
- TopLevelFlag(..), isTopLevel, isNotTopLevel
+
+ TopLevelFlag(..), isTopLevel, isNotTopLevel,
+
+ Boxity(..), isBoxed, tupleParens,
+
+ OccInfo(..), seqOccInfo, isFragileOcc, isDeadOcc, isLoopBreaker,
+
+ InsideLam, insideLam, notInsideLam,
+ OneBranch, oneBranch, notOneBranch,
+
+ EP(..)
) where
#include "HsVersions.h"
\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}
data NewOrData
= NewType -- "newtype Blah ..."
| DataType -- "data Blah ..."
- | EnumType -- Enumeration; all constructors are nullary
deriving( Eq ) -- Needed because Demand derives Eq
\end{code}
%************************************************************************
%* *
+\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}
%* *
%************************************************************************
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.
+
+
+%************************************************************************
+%* *
+\subsection{Occurrence information}
+%* *
+%************************************************************************
+
+This data type is used exclusively by the simplifier, but it appears in a
+SubstResult, which is currently defined in VarEnv, which is pretty near
+the base of the module hierarchy. So it seemed simpler to put the
+defn of OccInfo here, safely at the bottom
+
+\begin{code}
+data OccInfo
+ = NoOccInfo
+
+ | IAmDead -- Marks unused variables. Sometimes useful for
+ -- lambda and case-bound variables.
+
+ | OneOcc InsideLam
+
+ OneBranch
+
+ | IAmALoopBreaker -- Used by the occurrence analyser to mark loop-breakers
+ -- in a group of recursive definitions
+
+seqOccInfo :: OccInfo -> ()
+seqOccInfo (OneOcc in_lam once) = in_lam `seq` once `seq` ()
+seqOccInfo occ = ()
+
+type InsideLam = Bool -- True <=> Occurs inside a non-linear lambda
+ -- Substituting a redex for this occurrence is
+ -- dangerous because it might duplicate work.
+insideLam = True
+notInsideLam = False
+
+type OneBranch = Bool -- True <=> Occurs in only one case branch
+ -- so no code-duplication issue to worry about
+oneBranch = True
+notOneBranch = 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}
+instance Outputable OccInfo where
+ -- only used for debugging; never parsed. KSW 1999-07
+ ppr NoOccInfo = empty
+ ppr IAmALoopBreaker = ptext SLIT("_Kx")
+ ppr IAmDead = ptext SLIT("_Kd")
+ ppr (OneOcc inside_lam one_branch) | inside_lam = ptext SLIT("_Kl")
+ | one_branch = ptext SLIT("_Ks")
+ | otherwise = ptext SLIT("_Ks*")
+
+instance Show OccInfo where
+ showsPrec p occ = showsPrecSDoc p (ppr occ)
+\end{code}
+
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