The @Class@ datatype
\begin{code}
-{-# OPTIONS -w #-}
--- The above warning supression flag is a temporary kludge.
--- While working on this module you are encouraged to remove it and fix
--- any warnings in the module. See
--- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
--- for details
-
module Class (
Class, ClassOpItem,
DefMeth (..),
+ defMethSpecOfDefMeth,
- FunDep, pprFundeps,
+ FunDep, pprFundeps, pprFunDep,
- mkClass, classTyVars, classArity,
- classKey, className, classATs, classSelIds, classTyCon, classMethods,
- classBigSig, classExtraBigSig, classTvsFds, classSCTheta
+ mkClass, classTyVars, classArity, classSCNEqs,
+ classKey, className, classATs, classTyCon, classMethods,
+ classOpItems, classBigSig, classExtraBigSig, classTvsFds, classSCTheta,
+ classAllSelIds, classSCSelId
) where
+#include "Typeable.h"
#include "HsVersions.h"
import {-# SOURCE #-} TyCon ( TyCon )
import Name
import BasicTypes
import Unique
+import Util
import Outputable
+import FastString
+
+import qualified Data.Data as Data
\end{code}
%************************************************************************
classTyVars :: [TyVar], -- The class type variables
classFunDeps :: [FunDep TyVar], -- The functional dependencies
- classSCTheta :: [PredType], -- Immediate superclasses, and the
- classSCSels :: [Id], -- corresponding selector functions
- -- to extract them from a dictionary
- -- of this class
-
+ -- Superclasses: eg: (F a ~ b, F b ~ G a, Eq a, Show b)
+ -- We need value-level selectors for the dictionary
+ -- superclasses, but not for the equality superclasses
+ classSCTheta :: [PredType], -- Immediate superclasses,
+ --- *with equalities first*
+ classSCNEqs :: Int, -- How many equalities
+ classSCSels :: [Id], -- Selector functions to extract the
+ -- *dictionary* superclasses from a
+ -- dictionary of this class
+ -- Associated types
classATs :: [TyCon], -- Associated type families
+ -- Class operations
classOpStuff :: [ClassOpItem], -- Ordered by tag
classTyCon :: TyCon -- The data type constructor for
-- Default-method info
data DefMeth = NoDefMeth -- No default method
- | DefMeth -- A polymorphic default method
- | GenDefMeth -- A generic default method
+ | DefMeth Name -- A polymorphic default method
+ | GenDefMeth Name -- A generic default method
deriving Eq
+
+-- | Convert a `DefMethSpec` to a `DefMeth`, which discards the name field in
+-- the `DefMeth` constructor of the `DefMeth`.
+defMethSpecOfDefMeth :: DefMeth -> DefMethSpec
+defMethSpecOfDefMeth meth
+ = case meth of
+ NoDefMeth -> NoDM
+ DefMeth _ -> VanillaDM
+ GenDefMeth _ -> GenericDM
+
\end{code}
The @mkClass@ function fills in the indirect superclasses.
\begin{code}
mkClass :: Name -> [TyVar]
-> [([TyVar], [TyVar])]
- -> [PredType] -> [Id]
+ -> [PredType] -> Int -> [Id]
-> [TyCon]
-> [ClassOpItem]
-> TyCon
-> Class
-mkClass name tyvars fds super_classes superdict_sels ats
+mkClass name tyvars fds super_classes n_eqs superdict_sels ats
op_stuff tycon
- = Class { classKey = getUnique name,
- className = name,
- classTyVars = tyvars,
+ = Class { classKey = getUnique name,
+ className = name,
+ classTyVars = tyvars,
classFunDeps = fds,
classSCTheta = super_classes,
- classSCSels = superdict_sels,
- classATs = ats,
+ classSCNEqs = n_eqs,
+ classSCSels = superdict_sels,
+ classATs = ats,
classOpStuff = op_stuff,
- classTyCon = tycon }
+ classTyCon = tycon }
\end{code}
%************************************************************************
classArity clas = length (classTyVars clas)
-- Could memoise this
-classSelIds :: Class -> [Id]
-classSelIds c@(Class {classSCSels = sc_sels})
+classAllSelIds :: Class -> [Id]
+-- Both superclass-dictionary and method selectors
+classAllSelIds c@(Class {classSCSels = sc_sels})
= sc_sels ++ classMethods c
+classSCSelId :: Class -> Int -> Id
+-- Get the n'th superclass selector Id
+-- where n is 0-indexed, and counts
+-- *all* superclasses including equalities
+classSCSelId (Class { classSCNEqs = n_eqs, classSCSels = sc_sels }) n
+ = ASSERT( sc_sel_index >= 0 && sc_sel_index < length sc_sels )
+ sc_sels !! sc_sel_index
+ where
+ sc_sel_index = n - n_eqs -- 0-index into classSCSels
+
classMethods :: Class -> [Id]
classMethods (Class {classOpStuff = op_stuff})
= [op_sel | (op_sel, _) <- op_stuff]
+classOpItems :: Class -> [ClassOpItem]
+classOpItems (Class { classOpStuff = op_stuff})
+ = op_stuff
+
+classTvsFds :: Class -> ([TyVar], [FunDep TyVar])
classTvsFds c
= (classTyVars c, classFunDeps c)
+classBigSig :: Class -> ([TyVar], [PredType], [Id], [ClassOpItem])
classBigSig (Class {classTyVars = tyvars, classSCTheta = sc_theta,
classSCSels = sc_sels, classOpStuff = op_stuff})
= (tyvars, sc_theta, sc_sels, op_stuff)
+
+classExtraBigSig :: Class -> ([TyVar], [FunDep TyVar], [PredType], [Id], [TyCon], [ClassOpItem])
classExtraBigSig (Class {classTyVars = tyvars, classFunDeps = fundeps,
classSCTheta = sc_theta, classSCSels = sc_sels,
classATs = ats, classOpStuff = op_stuff})
showsPrec p c = showsPrecSDoc p (ppr c)
instance Outputable DefMeth where
- ppr DefMeth = text "{- has default method -}"
- ppr GenDefMeth = text "{- has generic method -}"
- ppr NoDefMeth = empty -- No default method
+ ppr (DefMeth n) = ptext (sLit "Default method") <+> ppr n
+ ppr (GenDefMeth n) = ptext (sLit "Generic default method") <+> ppr n
+ ppr NoDefMeth = empty -- No default method
pprFundeps :: Outputable a => [FunDep a] -> SDoc
pprFundeps [] = empty
-pprFundeps fds = hsep (ptext SLIT("|") : punctuate comma (map ppr_fd fds))
- where
- ppr_fd (us, vs) = hsep [interppSP us, ptext SLIT("->"),
- interppSP vs]
+pprFundeps fds = hsep (ptext (sLit "|") : punctuate comma (map pprFunDep fds))
+
+pprFunDep :: Outputable a => FunDep a -> SDoc
+pprFunDep (us, vs) = hsep [interppSP us, ptext (sLit "->"), interppSP vs]
+
+instance Data.Typeable Class where
+ typeOf _ = Data.mkTyConApp (Data.mkTyCon "Class") []
+
+instance Data.Data Class where
+ -- don't traverse?
+ toConstr _ = abstractConstr "Class"
+ gunfold _ _ = error "gunfold"
+ dataTypeOf _ = mkNoRepType "Class"
\end{code}
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