2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[Class]{The @Class@ datatype}
11 classKey, className, classSelIds, classTyCon,
12 classBigSig, classExtraBigSig, classInstEnv, classTvsFds
15 #include "HsVersions.h"
17 import {-# SOURCE #-} TyCon ( TyCon )
18 import {-# SOURCE #-} TypeRep ( Type )
19 import {-# SOURCE #-} InstEnv ( InstEnv )
21 import Var ( Id, TyVar )
22 import Name ( NamedThing(..), Name )
23 import Unique ( Unique, Uniquable(..) )
28 %************************************************************************
30 \subsection[Class-basic]{@Class@: basic definition}
32 %************************************************************************
34 A @Class@ corresponds to a Greek kappa in the static semantics:
39 classKey :: Unique, -- Key for fast comparison
42 classTyVars :: [TyVar], -- The class type variables
43 classFunDeps :: [([TyVar], [TyVar])], -- The functional dependencies
45 classSCTheta :: [(Class,[Type])], -- Immediate superclasses, and the
46 classSCSels :: [Id], -- corresponding selector functions to
47 -- extract them from a dictionary of this
50 classOpStuff :: [ClassOpItem], -- Ordered by tag
52 classInstEnv :: InstEnv, -- All the instances of this class
54 classTyCon :: TyCon -- The data type constructor for dictionaries
57 type ClassOpItem = (Id, -- Selector function; contains unfolding
58 Id, -- Default methods
59 Bool) -- True <=> an explicit default method was
60 -- supplied in the class decl
63 The @mkClass@ function fills in the indirect superclasses.
66 mkClass :: Name -> [TyVar]
67 -> [([TyVar], [TyVar])]
68 -> [(Class,[Type])] -> [Id]
74 mkClass name tyvars fds super_classes superdict_sels
75 op_stuff tycon class_insts
76 = Class { classKey = getUnique name,
80 classSCTheta = super_classes,
81 classSCSels = superdict_sels,
82 classOpStuff = op_stuff,
83 classInstEnv = class_insts,
87 %************************************************************************
89 \subsection[Class-selectors]{@Class@: simple selectors}
91 %************************************************************************
93 The rest of these functions are just simple selectors.
96 classSelIds (Class {classSCSels = sc_sels, classOpStuff = op_stuff})
97 = sc_sels ++ [op_sel | (op_sel, _, _) <- op_stuff]
100 = (classTyVars c, classFunDeps c)
102 classBigSig (Class {classTyVars = tyvars, classSCTheta = sc_theta,
103 classSCSels = sc_sels, classOpStuff = op_stuff})
104 = (tyvars, sc_theta, sc_sels, op_stuff)
105 classExtraBigSig (Class {classTyVars = tyvars, classFunDeps = fundeps,
106 classSCTheta = sc_theta, classSCSels = sc_sels,
107 classOpStuff = op_stuff})
108 = (tyvars, fundeps, sc_theta, sc_sels, op_stuff)
112 %************************************************************************
114 \subsection[Class-instances]{Instance declarations for @Class@}
116 %************************************************************************
118 We compare @Classes@ by their keys (which include @Uniques@).
121 instance Eq Class where
122 c1 == c2 = classKey c1 == classKey c2
123 c1 /= c2 = classKey c1 /= classKey c2
125 instance Ord Class where
126 c1 <= c2 = classKey c1 <= classKey c2
127 c1 < c2 = classKey c1 < classKey c2
128 c1 >= c2 = classKey c1 >= classKey c2
129 c1 > c2 = classKey c1 > classKey c2
130 compare c1 c2 = classKey c1 `compare` classKey c2
134 instance Uniquable Class where
135 getUnique c = classKey c
137 instance NamedThing Class where
138 getName clas = className clas
140 instance Outputable Class where
141 ppr c = ppr (getName c)
143 instance Show Class where
144 showsPrec p c = showsPrecSDoc p (ppr c)