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,
11 #include "HsVersions.h"
14 HsType(..), HsTyVar(..),
15 SYN_IE(Context), SYN_IE(ClassAssertion)
18 , getTyVarName, replaceTyVarName
21 , cmpHsType, cmpContext
26 import Outputable ( interppSP, ifnotPprForUser )
27 import Kind ( Kind {- instance Outputable -} )
29 import Util ( thenCmp, cmpList, isIn, panic# )
32 This is the syntax for types as seen in type signatures.
35 type Context name = [ClassAssertion name]
37 type ClassAssertion name = (name, HsType name)
38 -- The type is usually a type variable, but it
39 -- doesn't have to be when reading interface files
42 = HsPreForAllTy (Context name)
45 -- The renamer turns HsPreForAllTys into HsForAllTys when they
46 -- occur in signatures, to make the binding of variables
47 -- explicit. This distinction is made visible for
48 -- non-COMPILING_GHC code, because you probably want to do the
51 | HsForAllTy [HsTyVar name]
55 | MonoTyVar name -- Type variable
57 | MonoTyApp name -- Type constructor or variable
60 -- We *could* have a "MonoTyCon name" equiv to "MonoTyApp name []"
61 -- (for efficiency, what?) WDP 96/02/18
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
106 instance (Outputable name) => Outputable (HsTyVar name) where
107 ppr sty (UserTyVar name) = ppr sty name
108 ppr sty (IfaceTyVar name kind) = ppCat [ppr sty name, ppStr "::", 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 = ppSep [ppStr "_forall_", ppBracket (interppSP sty tvs),
115 pprContext sty ctxt, ppStr "=>",
118 pprContext :: (Outputable name) => PprStyle -> (Context name) -> Pretty
119 pprContext sty [] = ppNil
120 pprContext sty context
121 = ppCat [ppCurlies (ppIntersperse pp'SP (map ppr_assert context))]
123 ppr_assert (clas, ty) = ppCat [ppr sty clas, ppr sty ty]
127 pREC_TOP = (0 :: Int)
128 pREC_FUN = (1 :: Int)
129 pREC_CON = (2 :: Int)
131 maybeParen :: Bool -> Pretty -> Pretty
132 maybeParen True p = ppParens p
133 maybeParen False p = p
135 -- printing works more-or-less as for Types
137 pprHsType, pprParendHsType :: (Outputable name) => PprStyle -> HsType name -> Pretty
139 pprHsType sty ty = ppr_mono_ty sty pREC_TOP ty
140 pprParendHsType sty ty = ppr_mono_ty sty pREC_CON ty
142 ppr_mono_ty sty ctxt_prec (HsPreForAllTy ctxt ty) = ppr_forall sty ctxt_prec [] ctxt ty
143 ppr_mono_ty sty ctxt_prec (HsForAllTy tvs ctxt ty) = ppr_forall sty ctxt_prec tvs ctxt ty
145 ppr_mono_ty sty ctxt_prec (MonoTyVar name) = ppr sty name
147 ppr_mono_ty sty ctxt_prec (MonoFunTy ty1 ty2)
148 = let p1 = ppr_mono_ty sty pREC_FUN ty1
149 p2 = ppr_mono_ty sty pREC_TOP ty2
151 maybeParen (ctxt_prec >= pREC_FUN)
152 (ppSep [p1, ppBeside (ppStr "-> ") p2])
154 ppr_mono_ty sty ctxt_prec (MonoTupleTy _ tys)
155 = ppParens (ppInterleave ppComma (map (ppr sty) tys))
157 ppr_mono_ty sty ctxt_prec (MonoListTy _ ty)
158 = ppBesides [ppLbrack, ppr_mono_ty sty pREC_TOP ty, ppRbrack]
160 ppr_mono_ty sty ctxt_prec (MonoTyApp tycon tys)
161 = let pp_tycon = ppr sty tycon in
165 maybeParen (ctxt_prec >= pREC_CON)
166 (ppCat [pp_tycon, ppInterleave ppNil (map (ppr_mono_ty sty pREC_CON) tys)])
168 ppr_mono_ty sty ctxt_prec (MonoDictTy clas ty)
169 = ppCurlies (ppCat [ppr sty clas, ppr_mono_ty sty pREC_CON ty])
170 -- Curlies are temporary
174 %************************************************************************
176 \subsection{Comparison}
178 %************************************************************************
180 We do define a specialised equality for these \tr{*Type} types; used
181 in checking interfaces. Most any other use is likely to be {\em
182 wrong}, so be careful!
185 cmpHsTyVar :: (a -> a -> TAG_) -> HsTyVar a -> HsTyVar a -> TAG_
186 cmpHsType :: (a -> a -> TAG_) -> HsType a -> HsType a -> TAG_
187 cmpContext :: (a -> a -> TAG_) -> Context a -> Context a -> TAG_
189 cmpHsTyVar cmp (UserTyVar v1) (UserTyVar v2) = v1 `cmp` v2
190 cmpHsTyVar cmp (IfaceTyVar v1 _) (IfaceTyVar v2 _) = v1 `cmp` v2
191 cmpHsTyVar cmp (UserTyVar _) other = LT_
192 cmpHsTyVar cmp other1 other2 = GT_
195 -- We assume that HsPreForAllTys have been smashed by now.
197 cmpHsType _ (HsPreForAllTy _ _) _ = panic# "cmpHsType:HsPreForAllTy:1st arg"
198 cmpHsType _ _ (HsPreForAllTy _ _) = panic# "cmpHsType:HsPreForAllTy:2nd arg"
201 cmpHsType cmp (HsForAllTy tvs1 c1 t1) (HsForAllTy tvs2 c2 t2)
202 = cmpList (cmpHsTyVar cmp) tvs1 tvs2 `thenCmp`
203 cmpContext cmp c1 c2 `thenCmp`
206 cmpHsType cmp (MonoTyVar n1) (MonoTyVar n2)
209 cmpHsType cmp (MonoTupleTy _ tys1) (MonoTupleTy _ tys2)
210 = cmpList (cmpHsType cmp) tys1 tys2
211 cmpHsType cmp (MonoListTy _ ty1) (MonoListTy _ ty2)
212 = cmpHsType cmp ty1 ty2
214 cmpHsType cmp (MonoTyApp tc1 tys1) (MonoTyApp tc2 tys2)
215 = cmp tc1 tc2 `thenCmp`
216 cmpList (cmpHsType cmp) tys1 tys2
218 cmpHsType cmp (MonoFunTy a1 b1) (MonoFunTy a2 b2)
219 = cmpHsType cmp a1 a2 `thenCmp` cmpHsType cmp b1 b2
221 cmpHsType cmp (MonoDictTy c1 ty1) (MonoDictTy c2 ty2)
222 = cmp c1 c2 `thenCmp` cmpHsType cmp ty1 ty2
224 cmpHsType cmp ty1 ty2 -- tags must be different
228 if tag1 _LT_ tag2 then LT_ else GT_
230 tag (MonoTyVar n1) = (ILIT(1) :: FAST_INT)
231 tag (MonoTupleTy _ tys1) = ILIT(2)
232 tag (MonoListTy _ ty1) = ILIT(3)
233 tag (MonoTyApp tc1 tys1) = ILIT(4)
234 tag (MonoFunTy a1 b1) = ILIT(5)
235 tag (MonoDictTy c1 ty1) = ILIT(7)
236 tag (HsForAllTy _ _ _) = ILIT(8)
237 tag (HsPreForAllTy _ _) = ILIT(9)
241 = cmpList cmp_ctxt a b
243 cmp_ctxt (c1, ty1) (c2, ty2)
244 = cmp c1 c2 `thenCmp` cmpHsType cmp ty1 ty2