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 -} )
28 import Name ( nameOccName )
30 import PprStyle ( PprStyle(..) )
31 import Util ( thenCmp, cmpList, isIn, panic# )
34 This is the syntax for types as seen in type signatures.
37 type Context name = [ClassAssertion name]
39 type ClassAssertion name = (name, HsType name)
40 -- The type is usually a type variable, but it
41 -- doesn't have to be when reading interface files
44 = HsPreForAllTy (Context name)
47 -- The renamer turns HsPreForAllTys into HsForAllTys when they
48 -- occur in signatures, to make the binding of variables
49 -- explicit. This distinction is made visible for
50 -- non-COMPILING_GHC code, because you probably want to do the
53 | HsForAllTy [HsTyVar name]
57 | MonoTyVar name -- Type variable
59 | MonoTyApp name -- Type constructor or variable
62 -- We *could* have a "MonoTyCon name" equiv to "MonoTyApp name []"
63 -- (for efficiency, what?) WDP 96/02/18
65 | MonoFunTy (HsType name) -- function type
68 | MonoListTy name -- The list TyCon name
69 (HsType name) -- Element type
71 | MonoTupleTy name -- The tuple TyCon name
72 [HsType name] -- Element types (length gives arity)
74 -- these next two are only used in unfoldings in interfaces
75 | MonoDictTy name -- Class
78 mkHsForAllTy [] [] ty = ty
79 mkHsForAllTy tvs ctxt ty = HsForAllTy tvs ctxt ty
83 | IfaceTyVar name Kind
84 -- *** NOTA BENE *** A "monotype" in a pragma can have
85 -- for-alls in it, (mostly to do with dictionaries). These
86 -- must be explicitly Kinded.
88 getTyVarName (UserTyVar n) = n
89 getTyVarName (IfaceTyVar n _) = n
91 replaceTyVarName :: HsTyVar name1 -> name2 -> HsTyVar name2
92 replaceTyVarName (UserTyVar n) n' = UserTyVar n'
93 replaceTyVarName (IfaceTyVar n k) n' = IfaceTyVar n' k
97 %************************************************************************
99 \subsection{Pretty printing}
101 %************************************************************************
105 instance (Outputable name) => Outputable (HsType name) where
108 instance (Outputable name) => Outputable (HsTyVar name) where
109 ppr sty (UserTyVar name) = ppr_hs_tyvar sty name
110 ppr sty (IfaceTyVar name kind) = ppCat [ppr_hs_tyvar sty name, ppStr "::", ppr sty kind]
114 ppr_hs_tyvar PprInterface tv_name = ppr PprForUser tv_name
115 ppr_hs_tyvar other_sty tv_name = ppr other_sty tv_name
117 ppr_forall sty ctxt_prec [] [] ty
118 = ppr_mono_ty sty ctxt_prec ty
119 ppr_forall sty ctxt_prec tvs ctxt ty
120 = ppSep [ppStr "_forall_", ppBracket (interppSP sty tvs),
121 pprContext sty ctxt, ppStr "=>",
124 pprContext :: (Outputable name) => PprStyle -> (Context name) -> Pretty
125 pprContext sty [] = ppNil
126 pprContext sty context
127 = ppCat [ppCurlies (ppIntersperse pp'SP (map ppr_assert context))]
129 ppr_assert (clas, ty) = ppCat [ppr sty clas, ppr sty ty]
133 pREC_TOP = (0 :: Int)
134 pREC_FUN = (1 :: Int)
135 pREC_CON = (2 :: Int)
137 maybeParen :: Bool -> Pretty -> Pretty
138 maybeParen True p = ppParens p
139 maybeParen False p = p
141 -- printing works more-or-less as for Types
143 pprHsType, pprParendHsType :: (Outputable name) => PprStyle -> HsType name -> Pretty
145 pprHsType sty ty = ppr_mono_ty sty pREC_TOP ty
146 pprParendHsType sty ty = ppr_mono_ty sty pREC_CON ty
148 ppr_mono_ty sty ctxt_prec (HsPreForAllTy ctxt ty) = ppr_forall sty ctxt_prec [] ctxt ty
149 ppr_mono_ty sty ctxt_prec (HsForAllTy tvs ctxt ty) = ppr_forall sty ctxt_prec tvs ctxt ty
151 ppr_mono_ty sty ctxt_prec (MonoTyVar name) = ppr_hs_tyvar sty name
153 ppr_mono_ty sty ctxt_prec (MonoFunTy ty1 ty2)
154 = let p1 = ppr_mono_ty sty pREC_FUN ty1
155 p2 = ppr_mono_ty sty pREC_TOP ty2
157 maybeParen (ctxt_prec >= pREC_FUN)
158 (ppSep [p1, ppBeside (ppStr "-> ") p2])
160 ppr_mono_ty sty ctxt_prec (MonoTupleTy _ tys)
161 = ppParens (ppInterleave ppComma (map (ppr sty) tys))
163 ppr_mono_ty sty ctxt_prec (MonoListTy _ ty)
164 = ppBesides [ppLbrack, ppr_mono_ty sty pREC_TOP ty, ppRbrack]
166 ppr_mono_ty sty ctxt_prec (MonoTyApp tycon tys)
167 = let pp_tycon = ppr sty tycon in
171 maybeParen (ctxt_prec >= pREC_CON)
172 (ppCat [pp_tycon, ppInterleave ppNil (map (ppr_mono_ty sty pREC_CON) tys)])
174 ppr_mono_ty sty ctxt_prec (MonoDictTy clas ty)
175 = ppCurlies (ppCat [ppr sty clas, ppr_mono_ty sty pREC_CON ty])
176 -- Curlies are temporary
180 %************************************************************************
182 \subsection{Comparison}
184 %************************************************************************
186 We do define a specialised equality for these \tr{*Type} types; used
187 in checking interfaces. Most any other use is likely to be {\em
188 wrong}, so be careful!
191 cmpHsTyVar :: (a -> a -> TAG_) -> HsTyVar a -> HsTyVar a -> TAG_
192 cmpHsType :: (a -> a -> TAG_) -> HsType a -> HsType a -> TAG_
193 cmpContext :: (a -> a -> TAG_) -> Context a -> Context a -> TAG_
195 cmpHsTyVar cmp (UserTyVar v1) (UserTyVar v2) = v1 `cmp` v2
196 cmpHsTyVar cmp (IfaceTyVar v1 _) (IfaceTyVar v2 _) = v1 `cmp` v2
197 cmpHsTyVar cmp (UserTyVar _) other = LT_
198 cmpHsTyVar cmp other1 other2 = GT_
201 -- We assume that HsPreForAllTys have been smashed by now.
203 cmpHsType _ (HsPreForAllTy _ _) _ = panic# "cmpHsType:HsPreForAllTy:1st arg"
204 cmpHsType _ _ (HsPreForAllTy _ _) = panic# "cmpHsType:HsPreForAllTy:2nd arg"
207 cmpHsType cmp (HsForAllTy tvs1 c1 t1) (HsForAllTy tvs2 c2 t2)
208 = cmpList (cmpHsTyVar cmp) tvs1 tvs2 `thenCmp`
209 cmpContext cmp c1 c2 `thenCmp`
212 cmpHsType cmp (MonoTyVar n1) (MonoTyVar n2)
215 cmpHsType cmp (MonoTupleTy _ tys1) (MonoTupleTy _ tys2)
216 = cmpList (cmpHsType cmp) tys1 tys2
217 cmpHsType cmp (MonoListTy _ ty1) (MonoListTy _ ty2)
218 = cmpHsType cmp ty1 ty2
220 cmpHsType cmp (MonoTyApp tc1 tys1) (MonoTyApp tc2 tys2)
221 = cmp tc1 tc2 `thenCmp`
222 cmpList (cmpHsType cmp) tys1 tys2
224 cmpHsType cmp (MonoFunTy a1 b1) (MonoFunTy a2 b2)
225 = cmpHsType cmp a1 a2 `thenCmp` cmpHsType cmp b1 b2
227 cmpHsType cmp (MonoDictTy c1 ty1) (MonoDictTy c2 ty2)
228 = cmp c1 c2 `thenCmp` cmpHsType cmp ty1 ty2
230 cmpHsType cmp ty1 ty2 -- tags must be different
234 if tag1 _LT_ tag2 then LT_ else GT_
236 tag (MonoTyVar n1) = (ILIT(1) :: FAST_INT)
237 tag (MonoTupleTy _ tys1) = ILIT(2)
238 tag (MonoListTy _ ty1) = ILIT(3)
239 tag (MonoTyApp tc1 tys1) = ILIT(4)
240 tag (MonoFunTy a1 b1) = ILIT(5)
241 tag (MonoDictTy c1 ty1) = ILIT(7)
242 tag (HsForAllTy _ _ _) = ILIT(8)
243 tag (HsPreForAllTy _ _) = ILIT(9)
247 = cmpList cmp_ctxt a b
249 cmp_ctxt (c1, ty1) (c2, ty2)
250 = cmp c1 c2 `thenCmp` cmpHsType cmp ty1 ty2