[project @ 2002-04-05 23:24:25 by sof]

[ghc-hetmet.git] / ghc / compiler / types / Class.lhs

diff --git a/ghc/compiler/types/Class.lhs b/ghc/compiler/types/Class.lhs
index 035a12c..6aced85 100644 (file)
--- a/ghc/compiler/types/Class.lhs
+++ b/ghc/compiler/types/Class.lhs
@@ -5,24 +5,26 @@
 
 \begin{code}
 module Class (
-       Class, ClassOpItem,
+       Class, ClassOpItem, FunDep,
+       DefMeth (..),
 
-       mkClass, classTyVars,
+       mkClass, classTyVars, classArity,
        classKey, className, classSelIds, classTyCon,
-       classBigSig, classExtraBigSig, classInstEnv, classTvsFds
+       classBigSig, classExtraBigSig, classTvsFds, classSCTheta,
+       classHasFDs
     ) where
 
 #include "HsVersions.h"
 
 import {-# SOURCE #-} TyCon    ( TyCon )
-import {-# SOURCE #-} TypeRep  ( Type )
-import {-# SOURCE #-} InstEnv  ( InstEnv )
+import {-# SOURCE #-} TypeRep  ( PredType )
 
 import Var             ( Id, TyVar )
 import Name            ( NamedThing(..), Name )
+import BasicTypes      ( Arity )
 import Unique          ( Unique, Uniquable(..) )
 import Outputable
-import Util
+import Util             ( notNull )
 \end{code}
 
 %************************************************************************
@@ -40,24 +42,29 @@ data Class
        className :: Name,
        
        classTyVars  :: [TyVar],                -- The class type variables
-       classFunDeps :: [([TyVar], [TyVar])],   -- The functional dependencies
+       classFunDeps :: [FunDep TyVar],         -- The functional dependencies
 
-       classSCTheta :: [(Class,[Type])],       -- Immediate superclasses, and the
+       classSCTheta :: [PredType],             -- Immediate superclasses, and the
        classSCSels  :: [Id],                   -- corresponding selector functions to
                                                -- extract them from a dictionary of this
                                                -- class
 
        classOpStuff :: [ClassOpItem],          -- Ordered by tag
 
-       classInstEnv :: InstEnv,        -- All the instances of this class
-
        classTyCon :: TyCon             -- The data type constructor for dictionaries
   }                                    -- of this class
 
-type ClassOpItem = (Id,        --   Selector function; contains unfolding
-                   Id,         --   Default methods
-                   Bool)       --   True <=> an explicit default method was 
-                               --            supplied in the class decl
+type FunDep a    = ([a],[a])   --  e.g. class C a b c |  a b -> c, a c -> b  where ...
+                               --  Here fun-deps are [([a,b],[c]), ([a,c],[b])]
+
+type ClassOpItem = (Id, DefMeth Name)
+       -- Selector function; contains unfolding
+       -- Default-method info
+
+data DefMeth id = NoDefMeth            -- No default method
+               | DefMeth id            -- A polymorphic default method (named id)
+               | GenDefMeth            -- A generic default method
+                deriving Eq  
 \end{code}
 
 The @mkClass@ function fills in the indirect superclasses.
@@ -65,14 +72,13 @@ The @mkClass@ function fills in the indirect superclasses.
 \begin{code}
 mkClass :: Name -> [TyVar]
        -> [([TyVar], [TyVar])]
-       -> [(Class,[Type])] -> [Id]
-       -> [(Id, Id, Bool)]
+       -> [PredType] -> [Id]
+       -> [ClassOpItem]
        -> TyCon
-       -> InstEnv
        -> Class
 
 mkClass name tyvars fds super_classes superdict_sels
-       op_stuff tycon class_insts
+       op_stuff tycon
   = Class {    classKey = getUnique name, 
                className = name,
                classTyVars = tyvars,
@@ -80,7 +86,6 @@ mkClass name tyvars fds super_classes superdict_sels
                classSCTheta = super_classes,
                classSCSels = superdict_sels,
                classOpStuff = op_stuff,
-               classInstEnv = class_insts,
                classTyCon = tycon }
 \end{code}
 
@@ -93,8 +98,12 @@ mkClass name tyvars fds super_classes superdict_sels
 The rest of these functions are just simple selectors.
 
 \begin{code}
+classArity :: Class -> Arity
+classArity clas = length (classTyVars clas)
+       -- Could memoise this
+
 classSelIds (Class {classSCSels = sc_sels, classOpStuff = op_stuff})
-  = sc_sels ++ [op_sel | (op_sel, _, _) <- op_stuff]
+  = sc_sels ++ [op_sel | (op_sel, _) <- op_stuff]
 
 classTvsFds c
   = (classTyVars c, classFunDeps c)
@@ -106,6 +115,9 @@ classExtraBigSig (Class {classTyVars = tyvars, classFunDeps = fundeps,
                         classSCTheta = sc_theta, classSCSels = sc_sels,
                         classOpStuff = op_stuff})
   = (tyvars, fundeps, sc_theta, sc_sels, op_stuff)
+
+classHasFDs :: Class -> Bool
+classHasFDs (Class {classFunDeps = fundeps}) = notNull fundeps
 \end{code}