2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[Class]{The @Class@ datatype}
11 classKey, classSelIds, classTyCon,
12 classBigSig, classInstEnv
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
44 classSCTheta :: [(Class,[Type])], -- Immediate superclasses, and the
45 classSCSels :: [Id], -- corresponding selector functions to
46 -- extract them from a dictionary of this
49 classOpStuff :: [ClassOpItem], -- Ordered by tag
51 classInstEnv :: InstEnv, -- All the instances of this class
53 classTyCon :: TyCon -- The data type constructor for dictionaries
56 type ClassOpItem = (Id, -- Selector function; contains unfolding
57 Id, -- Default methods
58 Bool) -- True <=> an explicit default method was
59 -- supplied in the class decl
62 The @mkClass@ function fills in the indirect superclasses.
65 mkClass :: Name -> [TyVar]
66 -> [(Class,[Type])] -> [Id]
72 mkClass name tyvars super_classes superdict_sels
73 op_stuff tycon class_insts
74 = Class { classKey = getUnique name,
77 classSCTheta = super_classes,
78 classSCSels = superdict_sels,
79 classOpStuff = op_stuff,
80 classInstEnv = class_insts,
84 %************************************************************************
86 \subsection[Class-selectors]{@Class@: simple selectors}
88 %************************************************************************
90 The rest of these functions are just simple selectors.
93 classSelIds (Class {classSCSels = sc_sels, classOpStuff = op_stuff})
94 = sc_sels ++ [op_sel | (op_sel, _, _) <- op_stuff]
96 classBigSig (Class {classTyVars = tyvars, classSCTheta = sc_theta,
97 classSCSels = sc_sels, classOpStuff = op_stuff})
98 = (tyvars, sc_theta, sc_sels, op_stuff)
102 %************************************************************************
104 \subsection[Class-instances]{Instance declarations for @Class@}
106 %************************************************************************
108 We compare @Classes@ by their keys (which include @Uniques@).
111 instance Eq Class where
112 c1 == c2 = classKey c1 == classKey c2
113 c1 /= c2 = classKey c1 /= classKey c2
115 instance Ord Class where
116 c1 <= c2 = classKey c1 <= classKey c2
117 c1 < c2 = classKey c1 < classKey c2
118 c1 >= c2 = classKey c1 >= classKey c2
119 c1 > c2 = classKey c1 > classKey c2
120 compare c1 c2 = classKey c1 `compare` classKey c2
124 instance Uniquable Class where
125 getUnique c = classKey c
127 instance NamedThing Class where
128 getName clas = className clas
130 instance Outputable Class where
131 ppr c = ppr (getName c)
133 instance Show Class where
134 showsPrec p c = showsPrecSDoc p (ppr c)