2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
15 mkClass, classTyVars, classArity,
16 classKey, className, classATs, classSelIds, classTyCon, classMethods,
17 classBigSig, classExtraBigSig, classTvsFds, classSCTheta
20 #include "HsVersions.h"
22 import {-# SOURCE #-} TyCon ( TyCon )
23 import {-# SOURCE #-} TypeRep ( PredType )
33 %************************************************************************
35 \subsection[Class-basic]{@Class@: basic definition}
37 %************************************************************************
39 A @Class@ corresponds to a Greek kappa in the static semantics:
44 classKey :: Unique, -- Key for fast comparison
47 classTyVars :: [TyVar], -- The class type variables
48 classFunDeps :: [FunDep TyVar], -- The functional dependencies
50 classSCTheta :: [PredType], -- Immediate superclasses, and the
51 classSCSels :: [Id], -- corresponding selector functions
52 -- to extract them from a dictionary
55 classATs :: [TyCon], -- Associated type families
57 classOpStuff :: [ClassOpItem], -- Ordered by tag
59 classTyCon :: TyCon -- The data type constructor for
60 -- dictionaries of this class
63 type FunDep a = ([a],[a]) -- e.g. class C a b c | a b -> c, a c -> b where...
64 -- Here fun-deps are [([a,b],[c]), ([a,c],[b])]
66 type ClassOpItem = (Id, DefMeth)
67 -- Selector function; contains unfolding
68 -- Default-method info
70 data DefMeth = NoDefMeth -- No default method
71 | DefMeth -- A polymorphic default method
72 | GenDefMeth -- A generic default method
76 The @mkClass@ function fills in the indirect superclasses.
79 mkClass :: Name -> [TyVar]
80 -> [([TyVar], [TyVar])]
87 mkClass name tyvars fds super_classes superdict_sels ats
89 = Class { classKey = getUnique name,
93 classSCTheta = super_classes,
94 classSCSels = superdict_sels,
96 classOpStuff = op_stuff,
100 %************************************************************************
102 \subsection[Class-selectors]{@Class@: simple selectors}
104 %************************************************************************
106 The rest of these functions are just simple selectors.
109 classArity :: Class -> Arity
110 classArity clas = length (classTyVars clas)
111 -- Could memoise this
113 classSelIds :: Class -> [Id]
114 classSelIds c@(Class {classSCSels = sc_sels})
115 = sc_sels ++ classMethods c
117 classMethods :: Class -> [Id]
118 classMethods (Class {classOpStuff = op_stuff})
119 = [op_sel | (op_sel, _) <- op_stuff]
121 classTvsFds :: Class -> ([TyVar], [FunDep TyVar])
123 = (classTyVars c, classFunDeps c)
125 classBigSig :: Class -> ([TyVar], [PredType], [Id], [ClassOpItem])
126 classBigSig (Class {classTyVars = tyvars, classSCTheta = sc_theta,
127 classSCSels = sc_sels, classOpStuff = op_stuff})
128 = (tyvars, sc_theta, sc_sels, op_stuff)
130 classExtraBigSig :: Class -> ([TyVar], [FunDep TyVar], [PredType], [Id], [TyCon], [ClassOpItem])
131 classExtraBigSig (Class {classTyVars = tyvars, classFunDeps = fundeps,
132 classSCTheta = sc_theta, classSCSels = sc_sels,
133 classATs = ats, classOpStuff = op_stuff})
134 = (tyvars, fundeps, sc_theta, sc_sels, ats, op_stuff)
138 %************************************************************************
140 \subsection[Class-instances]{Instance declarations for @Class@}
142 %************************************************************************
144 We compare @Classes@ by their keys (which include @Uniques@).
147 instance Eq Class where
148 c1 == c2 = classKey c1 == classKey c2
149 c1 /= c2 = classKey c1 /= classKey c2
151 instance Ord Class where
152 c1 <= c2 = classKey c1 <= classKey c2
153 c1 < c2 = classKey c1 < classKey c2
154 c1 >= c2 = classKey c1 >= classKey c2
155 c1 > c2 = classKey c1 > classKey c2
156 compare c1 c2 = classKey c1 `compare` classKey c2
160 instance Uniquable Class where
161 getUnique c = classKey c
163 instance NamedThing Class where
164 getName clas = className clas
166 instance Outputable Class where
167 ppr c = ppr (getName c)
169 instance Show Class where
170 showsPrec p c = showsPrecSDoc p (ppr c)
172 instance Outputable DefMeth where
173 ppr DefMeth = text "{- has default method -}"
174 ppr GenDefMeth = text "{- has generic method -}"
175 ppr NoDefMeth = empty -- No default method
177 pprFundeps :: Outputable a => [FunDep a] -> SDoc
178 pprFundeps [] = empty
179 pprFundeps fds = hsep (ptext SLIT("|") : punctuate comma (map ppr_fd fds))
181 ppr_fd (us, vs) = hsep [interppSP us, ptext SLIT("->"),