2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
4 \section[HsTypes]{Abstract syntax: user-defined types}
6 If compiled without \tr{#define COMPILING_GHC}, you get
7 (part of) a Haskell-abstract-syntax library. With it,
9 [OLD COMMENT -- SOF 7/97]
12 #include "HsVersions.h"
15 HsType(..), HsTyVar(..),
16 SYN_IE(Context), SYN_IE(ClassAssertion)
19 , getTyVarName, replaceTyVarName
22 , cmpHsType, cmpContext
27 import CmdLineOpts ( opt_PprUserLength )
28 import Outputable ( Outputable(..), PprStyle(..), pprQuote, interppSP )
29 import Kind ( Kind {- instance Outputable -} )
30 import Name ( nameOccName )
32 import Util ( thenCmp, cmpList, isIn, panic# )
35 This is the syntax for types as seen in type signatures.
38 type Context name = [ClassAssertion name]
40 type ClassAssertion name = (name, HsType name)
41 -- The type is usually a type variable, but it
42 -- doesn't have to be when reading interface files
45 = HsPreForAllTy (Context name)
48 -- The renamer turns HsPreForAllTys into HsForAllTys when they
49 -- occur in signatures, to make the binding of variables
50 -- explicit. This distinction is made visible for
51 -- non-COMPILING_GHC code, because you probably want to do the
54 | HsForAllTy [HsTyVar name]
58 | MonoTyVar name -- Type variable
60 | MonoTyApp (HsType name)
63 | MonoFunTy (HsType name) -- function type
66 | MonoListTy name -- The list TyCon name
67 (HsType name) -- Element type
69 | MonoTupleTy name -- The tuple TyCon name
70 [HsType name] -- Element types (length gives arity)
72 -- these next two are only used in unfoldings in interfaces
73 | MonoDictTy name -- Class
76 mkHsForAllTy [] [] ty = ty
77 mkHsForAllTy tvs ctxt ty = HsForAllTy tvs ctxt ty
81 | IfaceTyVar name Kind
82 -- *** NOTA BENE *** A "monotype" in a pragma can have
83 -- for-alls in it, (mostly to do with dictionaries). These
84 -- must be explicitly Kinded.
86 getTyVarName (UserTyVar n) = n
87 getTyVarName (IfaceTyVar n _) = n
89 replaceTyVarName :: HsTyVar name1 -> name2 -> HsTyVar name2
90 replaceTyVarName (UserTyVar n) n' = UserTyVar n'
91 replaceTyVarName (IfaceTyVar n k) n' = IfaceTyVar n' k
95 %************************************************************************
97 \subsection{Pretty printing}
99 %************************************************************************
103 instance (Outputable name) => Outputable (HsType name) where
104 ppr sty ty = pprQuote sty $ \ sty -> pprHsType sty ty
106 instance (Outputable name) => Outputable (HsTyVar name) where
107 ppr sty (UserTyVar name) = ppr sty name
108 ppr sty (IfaceTyVar name kind) = pprQuote sty $ \ sty ->
109 hsep [ppr sty name, ptext SLIT("::"), ppr sty kind]
111 ppr_forall sty ctxt_prec [] [] ty
112 = ppr_mono_ty sty ctxt_prec ty
113 ppr_forall sty ctxt_prec tvs ctxt ty
114 = maybeParen (ctxt_prec >= pREC_FUN) $
115 sep [ptext SLIT("_forall_"), brackets (interppSP sty tvs),
116 pprContext sty ctxt, ptext SLIT("=>"),
119 pprContext :: (Outputable name) => PprStyle -> (Context name) -> Doc
120 pprContext sty [] = empty
121 pprContext sty context
122 = pprQuote sty $ \ sty -> parens (hsep (punctuate comma (map ppr_assert context)))
124 ppr_assert (clas, ty) = hsep [ppr sty clas, ppr sty ty]
128 pREC_TOP = (0 :: Int)
129 pREC_FUN = (1 :: Int)
130 pREC_CON = (2 :: Int)
132 maybeParen :: Bool -> Doc -> Doc
133 maybeParen True p = parens p
134 maybeParen False p = p
136 -- printing works more-or-less as for Types
138 pprHsType, pprParendHsType :: (Outputable name) => PprStyle -> HsType name -> Doc
140 pprHsType sty ty = ppr_mono_ty sty pREC_TOP ty
141 pprParendHsType sty ty = ppr_mono_ty sty pREC_CON ty
143 ppr_mono_ty sty ctxt_prec (HsPreForAllTy ctxt ty) = ppr_forall sty ctxt_prec [] ctxt ty
144 ppr_mono_ty sty ctxt_prec (HsForAllTy tvs ctxt ty) = ppr_forall sty ctxt_prec tvs ctxt ty
146 ppr_mono_ty sty ctxt_prec (MonoTyVar name) = ppr sty name
148 ppr_mono_ty sty ctxt_prec (MonoFunTy ty1 ty2)
149 = let p1 = ppr_mono_ty sty pREC_FUN ty1
150 p2 = ppr_mono_ty sty pREC_TOP ty2
152 maybeParen (ctxt_prec >= pREC_FUN)
153 (sep [p1, (<>) (ptext SLIT("-> ")) p2])
155 ppr_mono_ty sty ctxt_prec (MonoTupleTy _ tys)
156 = parens (sep (punctuate comma (map (ppr sty) tys)))
158 ppr_mono_ty sty ctxt_prec (MonoListTy _ ty)
159 = brackets (ppr_mono_ty sty pREC_TOP ty)
161 ppr_mono_ty sty ctxt_prec (MonoTyApp fun_ty arg_ty)
162 = maybeParen (ctxt_prec >= pREC_CON)
163 (hsep [ppr_mono_ty sty pREC_FUN fun_ty, ppr_mono_ty sty pREC_CON arg_ty])
165 ppr_mono_ty sty ctxt_prec (MonoDictTy clas ty)
166 = hsep [ppr sty clas, ppr_mono_ty sty pREC_CON ty]
170 %************************************************************************
172 \subsection{Comparison}
174 %************************************************************************
176 We do define a specialised equality for these \tr{*Type} types; used
177 in checking interfaces. Most any other use is likely to be {\em
178 wrong}, so be careful!
181 cmpHsTyVar :: (a -> a -> TAG_) -> HsTyVar a -> HsTyVar a -> TAG_
182 --cmpHsType :: (a -> a -> TAG_) -> HsType a -> HsType a -> TAG_
183 --cmpContext :: (a -> a -> TAG_) -> Context a -> Context a -> TAG_
185 cmpHsTyVar cmp (UserTyVar v1) (UserTyVar v2) = v1 `cmp` v2
186 cmpHsTyVar cmp (IfaceTyVar v1 _) (IfaceTyVar v2 _) = v1 `cmp` v2
187 cmpHsTyVar cmp (UserTyVar _) other = LT_
188 cmpHsTyVar cmp other1 other2 = GT_
191 -- We assume that HsPreForAllTys have been smashed by now.
193 cmpHsType _ (HsPreForAllTy _ _) _ = panic# "cmpHsType:HsPreForAllTy:1st arg"
194 cmpHsType _ _ (HsPreForAllTy _ _) = panic# "cmpHsType:HsPreForAllTy:2nd arg"
197 cmpHsType cmp (HsForAllTy tvs1 c1 t1) (HsForAllTy tvs2 c2 t2)
198 = cmpList (cmpHsTyVar cmp) tvs1 tvs2 `thenCmp`
199 cmpContext cmp c1 c2 `thenCmp`
202 cmpHsType cmp (MonoTyVar n1) (MonoTyVar n2)
205 cmpHsType cmp (MonoTupleTy _ tys1) (MonoTupleTy _ tys2)
206 = cmpList (cmpHsType cmp) tys1 tys2
207 cmpHsType cmp (MonoListTy _ ty1) (MonoListTy _ ty2)
208 = cmpHsType cmp ty1 ty2
210 cmpHsType cmp (MonoTyApp fun_ty1 arg_ty1) (MonoTyApp fun_ty2 arg_ty2)
211 = cmpHsType cmp fun_ty1 fun_ty2 `thenCmp` cmpHsType cmp arg_ty1 arg_ty2
213 cmpHsType cmp (MonoFunTy a1 b1) (MonoFunTy a2 b2)
214 = cmpHsType cmp a1 a2 `thenCmp` cmpHsType cmp b1 b2
216 cmpHsType cmp (MonoDictTy c1 ty1) (MonoDictTy c2 ty2)
217 = cmp c1 c2 `thenCmp` cmpHsType cmp ty1 ty2
219 cmpHsType cmp ty1 ty2 -- tags must be different
223 if tag1 _LT_ tag2 then LT_ else GT_
225 tag (MonoTyVar n1) = (ILIT(1) :: FAST_INT)
226 tag (MonoTupleTy _ tys1) = ILIT(2)
227 tag (MonoListTy _ ty1) = ILIT(3)
228 tag (MonoTyApp tc1 tys1) = ILIT(4)
229 tag (MonoFunTy a1 b1) = ILIT(5)
230 tag (MonoDictTy c1 ty1) = ILIT(7)
231 tag (HsForAllTy _ _ _) = ILIT(8)
232 tag (HsPreForAllTy _ _) = ILIT(9)
236 = cmpList cmp_ctxt a b
238 cmp_ctxt (c1, ty1) (c2, ty2)
239 = cmp c1 c2 `thenCmp` cmpHsType cmp ty1 ty2