2 % (c) The AQUA Project, Glasgow University, 1996-1998
4 \section[PprType]{Printing Types, TyVars, Classes, TyCons}
8 pprKind, pprParendKind,
9 pprType, pprParendType,
10 pprSourceType, pprPred, pprTheta, pprClassPred,
11 pprTyVarBndr, pprTyVarBndrs,
14 getTyDescription, showTypeCategory
17 #include "HsVersions.h"
20 -- (PprType can see all the representations it's trying to print)
21 import TypeRep ( Type(..), TyNote(..), Kind, liftedTypeKind ) -- friend
22 import Type ( SourceType(..), isUTyVar, eqKind )
23 import TcType ( ThetaType, PredType, tcSplitPredTy_maybe,
24 tcSplitSigmaTy, isPredTy, isDictTy,
25 tcSplitTyConApp_maybe, tcSplitFunTy_maybe
27 import Var ( TyVar, tyVarKind )
28 import Class ( Class )
29 import TyCon ( TyCon, isPrimTyCon, isTupleTyCon, tupleTyConBoxity,
30 maybeTyConSingleCon, isEnumerationTyCon,
35 import CmdLineOpts ( opt_PprStyle_RawTypes )
36 import Maybes ( maybeToBool )
37 import Name ( getOccString, getOccName )
39 import Unique ( Uniquable(..) )
40 import BasicTypes ( tupleParens )
41 import PrelNames -- quite a few *Keys
44 %************************************************************************
46 \subsection{The external interface}
48 %************************************************************************
50 @pprType@ is the standard @Type@ printer; the overloaded @ppr@ function is
51 defined to use this. @pprParendType@ is the same, except it puts
52 parens around the type, except for the atomic cases. @pprParendType@
53 works just by setting the initial context precedence very high.
56 pprType, pprParendType :: Type -> SDoc
57 pprType ty = ppr_ty tOP_PREC ty
58 pprParendType ty = ppr_ty tYCON_PREC ty
60 pprKind, pprParendKind :: Kind -> SDoc
62 pprParendKind = pprParendType
64 pprPred :: PredType -> SDoc
65 pprPred = pprSourceType
67 pprSourceType :: SourceType -> SDoc
68 pprSourceType (ClassP clas tys) = pprClassPred clas tys
69 pprSourceType (IParam n ty) = hsep [ptext SLIT("?") <> ppr n,
70 ptext SLIT("::"), ppr ty]
71 pprSourceType (NType tc tys) = ppr tc <+> hsep (map pprParendType tys)
73 pprClassPred :: Class -> [Type] -> SDoc
74 pprClassPred clas tys = ppr clas <+> hsep (map pprParendType tys)
76 pprTheta :: ThetaType -> SDoc
77 pprTheta theta = parens (hsep (punctuate comma (map pprPred theta)))
79 instance Outputable Type where
82 instance Outputable PredType where
87 %************************************************************************
89 \subsection{Pretty printing}
91 %************************************************************************
95 @ppr_ty@ takes an @Int@ that is the precedence of the context.
96 The precedence levels are:
98 \item[tOP_PREC] No parens required.
99 \item[fUN_PREC] Left hand argument of a function arrow.
100 \item[tYCON_PREC] Argument of a type constructor.
105 tOP_PREC = (0 :: Int) -- type in ParseIface.y
106 fUN_PREC = (1 :: Int) -- btype in ParseIface.y
107 tYCON_PREC = (2 :: Int) -- atype in ParseIface.y
109 maybeParen ctxt_prec inner_prec pretty
110 | ctxt_prec < inner_prec = pretty
111 | otherwise = parens pretty
115 ppr_ty :: Int -> Type -> SDoc
116 ppr_ty ctxt_prec (TyVarTy tyvar)
119 ppr_ty ctxt_prec ty@(TyConApp tycon tys)
120 -- KIND CASE; it's of the form (Type x)
121 | tycon `hasKey` typeConKey,
123 = -- For kinds, print (Type x) as just x if x is a
124 -- type constructor (must be Boxed, Unboxed, AnyBox)
125 -- Otherwise print as (Type x)
127 TyConApp bx [] -> ppr (getOccName bx) -- Always unqualified
128 other -> maybeParen ctxt_prec tYCON_PREC
129 (ppr tycon <+> ppr_ty tYCON_PREC ty)
132 | (tycon `hasKey` usOnceTyConKey || tycon `hasKey` usManyTyConKey),
134 = -- For usages (! and .), always print bare OccName, without pkg/mod/uniq
135 ppr (getOccName (tyConName tycon))
137 -- TUPLE CASE (boxed and unboxed)
138 | isTupleTyCon tycon,
139 length tys == tyConArity tycon -- No magic if partially applied
140 = tupleParens (tupleTyConBoxity tycon)
141 (sep (punctuate comma (map (ppr_ty tOP_PREC) tys)))
144 | tycon `hasKey` listTyConKey,
146 = brackets (ppr_ty tOP_PREC ty)
150 = ppr_tc_app ctxt_prec tycon tys
153 ppr_ty ctxt_prec ty@(ForAllTy _ _)
154 = getPprStyle $ \ sty ->
155 maybeParen ctxt_prec fUN_PREC $
156 sep [ ptext SLIT("forall") <+> pp_tyvars sty <> ptext SLIT("."),
161 (tyvars, theta, tau) = tcSplitSigmaTy ty
163 pp_tyvars sty = sep (map pprTyVarBndr some_tyvars)
165 some_tyvars | userStyle sty && not opt_PprStyle_RawTypes
166 = filter (not . isUTyVar) tyvars -- hide uvars from user
171 ppr_theta theta = pprTheta theta <+> ptext SLIT("=>")
174 ppr_ty ctxt_prec (FunTy ty1 ty2)
175 -- we don't want to lose usage annotations or synonyms,
176 -- so we mustn't use splitFunTys here.
177 = maybeParen ctxt_prec fUN_PREC $
178 sep [ ppr_ty fUN_PREC ty1
179 , ptext arrow <+> ppr_ty tOP_PREC ty2
181 where arrow | isPredTy ty1 = SLIT("=>")
182 | otherwise = SLIT("->")
184 ppr_ty ctxt_prec (AppTy ty1 ty2)
185 = maybeParen ctxt_prec tYCON_PREC $
186 ppr_ty fUN_PREC ty1 <+> ppr_ty tYCON_PREC ty2
188 ppr_ty ctxt_prec (UsageTy u ty)
189 = maybeParen ctxt_prec tYCON_PREC $
190 ptext SLIT("__u") <+> ppr_ty tYCON_PREC u
191 <+> ppr_ty tYCON_PREC ty
192 -- fUN_PREC would be logical for u, but it yields a reduce/reduce conflict with AppTy
194 ppr_ty ctxt_prec (NoteTy (SynNote ty) expansion)
195 = ppr_ty ctxt_prec ty
196 -- = ppr_ty ctxt_prec expansion -- if we don't want to see syntys
198 ppr_ty ctxt_prec (NoteTy (FTVNote _) ty) = ppr_ty ctxt_prec ty
200 ppr_ty ctxt_prec (SourceTy (NType tc tys)) = ppr_tc_app ctxt_prec tc tys
201 ppr_ty ctxt_prec (SourceTy pred) = braces (pprPred pred)
203 ppr_tc_app ctxt_prec tc [] = ppr tc
204 ppr_tc_app ctxt_prec tc tys = maybeParen ctxt_prec tYCON_PREC
205 (sep [ppr tc, nest 4 (sep (map (ppr_ty tYCON_PREC) tys))])
209 %************************************************************************
211 \subsection[TyVar]{@TyVar@}
213 %************************************************************************
215 We print type-variable binders with their kinds in interface files,
216 and when in debug mode.
219 pprTyVarBndr :: TyVar -> SDoc
221 = getPprStyle $ \ sty ->
222 if (ifaceStyle sty && not (kind `eqKind` liftedTypeKind)) || debugStyle sty then
223 hsep [ppr tyvar, dcolon, pprParendKind kind]
224 -- See comments with ppDcolon in PprCore.lhs
228 kind = tyVarKind tyvar
230 pprTyVarBndrs tyvars = hsep (map pprTyVarBndr tyvars)
234 %************************************************************************
236 \subsection{Mumbo jumbo}
238 %************************************************************************
240 Grab a name for the type. This is used to determine the type
241 description for profiling.
244 getTyDescription :: Type -> String
247 = case (tcSplitSigmaTy ty) of { (_, _, tau_ty) ->
250 AppTy fun _ -> getTyDescription fun
251 FunTy _ res -> '-' : '>' : fun_result res
252 TyConApp tycon _ -> getOccString tycon
253 NoteTy (FTVNote _) ty -> getTyDescription ty
254 NoteTy (SynNote ty1) _ -> getTyDescription ty1
255 SourceTy sty -> getSourceTyDescription sty
256 ForAllTy _ ty -> getTyDescription ty
259 fun_result (FunTy _ res) = '>' : fun_result res
260 fun_result other = getTyDescription other
262 getSourceTyDescription (ClassP cl tys) = getOccString cl
263 getSourceTyDescription (NType tc tys) = getOccString tc
264 getSourceTyDescription (IParam id ty) = getOccString id
269 showTypeCategory :: Type -> Char
271 {C,I,F,D} char, int, float, double
273 S other single-constructor type
274 {c,i,f,d} unboxed ditto
276 s *unpacked" single-cons...
282 + dictionary, unless it's a ...
285 M other (multi-constructor) data-con type
287 - reserved for others to mark as "uninteresting"
293 case tcSplitTyConApp_maybe ty of
294 Nothing -> if maybeToBool (tcSplitFunTy_maybe ty)
299 let utc = getUnique tycon in
300 if utc == charDataConKey then 'C'
301 else if utc == intDataConKey then 'I'
302 else if utc == floatDataConKey then 'F'
303 else if utc == doubleDataConKey then 'D'
304 else if utc == smallIntegerDataConKey ||
305 utc == largeIntegerDataConKey then 'J'
306 else if utc == charPrimTyConKey then 'c'
307 else if (utc == intPrimTyConKey || utc == wordPrimTyConKey
308 || utc == addrPrimTyConKey) then 'i'
309 else if utc == floatPrimTyConKey then 'f'
310 else if utc == doublePrimTyConKey then 'd'
311 else if isPrimTyCon tycon {- array, we hope -} then 'A' -- Bogus
312 else if isEnumerationTyCon tycon then 'E'
313 else if isTupleTyCon tycon then 'T'
314 else if maybeToBool (maybeTyConSingleCon tycon) then 'S'
315 else if utc == listTyConKey then 'L'
316 else 'M' -- oh, well...