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 import {-# SOURCE #-} TyCon ( TyCon )
21 import {-# SOURCE #-} TypeRep ( PredType )
31 %************************************************************************
33 \subsection[Class-basic]{@Class@: basic definition}
35 %************************************************************************
37 A @Class@ corresponds to a Greek kappa in the static semantics:
42 classKey :: Unique, -- Key for fast comparison
45 classTyVars :: [TyVar], -- The class type variables
46 classFunDeps :: [FunDep TyVar], -- The functional dependencies
48 classSCTheta :: [PredType], -- Immediate superclasses, and the
49 classSCSels :: [Id], -- corresponding selector functions
50 -- to extract them from a dictionary
53 classATs :: [TyCon], -- Associated type families
55 classOpStuff :: [ClassOpItem], -- Ordered by tag
57 classTyCon :: TyCon -- The data type constructor for
58 -- dictionaries of this class
61 type FunDep a = ([a],[a]) -- e.g. class C a b c | a b -> c, a c -> b where...
62 -- Here fun-deps are [([a,b],[c]), ([a,c],[b])]
64 type ClassOpItem = (Id, DefMeth)
65 -- Selector function; contains unfolding
66 -- Default-method info
68 data DefMeth = NoDefMeth -- No default method
69 | DefMeth -- A polymorphic default method
70 | GenDefMeth -- A generic default method
74 The @mkClass@ function fills in the indirect superclasses.
77 mkClass :: Name -> [TyVar]
78 -> [([TyVar], [TyVar])]
85 mkClass name tyvars fds super_classes superdict_sels ats
87 = Class { classKey = getUnique name,
91 classSCTheta = super_classes,
92 classSCSels = superdict_sels,
94 classOpStuff = op_stuff,
98 %************************************************************************
100 \subsection[Class-selectors]{@Class@: simple selectors}
102 %************************************************************************
104 The rest of these functions are just simple selectors.
107 classArity :: Class -> Arity
108 classArity clas = length (classTyVars clas)
109 -- Could memoise this
111 classSelIds :: Class -> [Id]
112 classSelIds c@(Class {classSCSels = sc_sels})
113 = sc_sels ++ classMethods c
115 classMethods :: Class -> [Id]
116 classMethods (Class {classOpStuff = op_stuff})
117 = [op_sel | (op_sel, _) <- op_stuff]
119 classTvsFds :: Class -> ([TyVar], [FunDep TyVar])
121 = (classTyVars c, classFunDeps c)
123 classBigSig :: Class -> ([TyVar], [PredType], [Id], [ClassOpItem])
124 classBigSig (Class {classTyVars = tyvars, classSCTheta = sc_theta,
125 classSCSels = sc_sels, classOpStuff = op_stuff})
126 = (tyvars, sc_theta, sc_sels, op_stuff)
128 classExtraBigSig :: Class -> ([TyVar], [FunDep TyVar], [PredType], [Id], [TyCon], [ClassOpItem])
129 classExtraBigSig (Class {classTyVars = tyvars, classFunDeps = fundeps,
130 classSCTheta = sc_theta, classSCSels = sc_sels,
131 classATs = ats, classOpStuff = op_stuff})
132 = (tyvars, fundeps, sc_theta, sc_sels, ats, op_stuff)
136 %************************************************************************
138 \subsection[Class-instances]{Instance declarations for @Class@}
140 %************************************************************************
142 We compare @Classes@ by their keys (which include @Uniques@).
145 instance Eq Class where
146 c1 == c2 = classKey c1 == classKey c2
147 c1 /= c2 = classKey c1 /= classKey c2
149 instance Ord Class where
150 c1 <= c2 = classKey c1 <= classKey c2
151 c1 < c2 = classKey c1 < classKey c2
152 c1 >= c2 = classKey c1 >= classKey c2
153 c1 > c2 = classKey c1 > classKey c2
154 compare c1 c2 = classKey c1 `compare` classKey c2
158 instance Uniquable Class where
159 getUnique c = classKey c
161 instance NamedThing Class where
162 getName clas = className clas
164 instance Outputable Class where
165 ppr c = ppr (getName c)
167 instance Show Class where
168 showsPrec p c = showsPrecSDoc p (ppr c)
170 instance Outputable DefMeth where
171 ppr DefMeth = text "{- has default method -}"
172 ppr GenDefMeth = text "{- has generic method -}"
173 ppr NoDefMeth = empty -- No default method
175 pprFundeps :: Outputable a => [FunDep a] -> SDoc
176 pprFundeps [] = empty
177 pprFundeps fds = hsep (ptext (sLit "|") : punctuate comma (map ppr_fd fds))
179 ppr_fd (us, vs) = hsep [interppSP us, ptext (sLit "->"),