2 % (c) The AQUA Project, Glasgow University, 1996-1998
4 \section[PprType]{Printing Types, TyVars, Classes, TyCons}
8 pprKind, pprParendKind,
9 pprType, pprParendType,
10 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 (ClassP clas tys) = pprClassPred clas tys
66 pprPred (IParam n ty) = hsep [ptext SLIT("?") <> ppr n,
67 ptext SLIT("::"), ppr ty]
69 pprClassPred :: Class -> [Type] -> SDoc
70 pprClassPred clas tys = ppr clas <+> hsep (map pprParendType tys)
72 pprTheta :: ThetaType -> SDoc
73 pprTheta theta = parens (hsep (punctuate comma (map pprPred theta)))
75 instance Outputable Type where
78 instance Outputable PredType where
83 %************************************************************************
85 \subsection{Pretty printing}
87 %************************************************************************
91 @ppr_ty@ takes an @Int@ that is the precedence of the context.
92 The precedence levels are:
94 \item[tOP_PREC] No parens required.
95 \item[fUN_PREC] Left hand argument of a function arrow.
96 \item[tYCON_PREC] Argument of a type constructor.
101 tOP_PREC = (0 :: Int) -- type in ParseIface.y
102 fUN_PREC = (1 :: Int) -- btype in ParseIface.y
103 tYCON_PREC = (2 :: Int) -- atype in ParseIface.y
105 maybeParen ctxt_prec inner_prec pretty
106 | ctxt_prec < inner_prec = pretty
107 | otherwise = parens pretty
111 ppr_ty :: Int -> Type -> SDoc
112 ppr_ty ctxt_prec (TyVarTy tyvar)
115 ppr_ty ctxt_prec ty@(TyConApp tycon tys)
116 -- KIND CASE; it's of the form (Type x)
117 | tycon `hasKey` typeConKey,
119 = -- For kinds, print (Type x) as just x if x is a
120 -- type constructor (must be Boxed, Unboxed, AnyBox)
121 -- Otherwise print as (Type x)
123 TyConApp bx [] -> ppr (getOccName bx) -- Always unqualified
124 other -> maybeParen ctxt_prec tYCON_PREC
125 (ppr tycon <+> ppr_ty tYCON_PREC ty)
128 | (tycon `hasKey` usOnceTyConKey || tycon `hasKey` usManyTyConKey),
130 = -- For usages (! and .), always print bare OccName, without pkg/mod/uniq
131 ppr (getOccName (tyConName tycon))
133 -- TUPLE CASE (boxed and unboxed)
134 | isTupleTyCon tycon,
135 length tys == tyConArity tycon -- No magic if partially applied
136 = tupleParens (tupleTyConBoxity tycon)
137 (sep (punctuate comma (map (ppr_ty tOP_PREC) tys)))
140 | tycon `hasKey` listTyConKey,
142 = brackets (ppr_ty tOP_PREC ty)
146 = ppr_tc_app ctxt_prec tycon tys
149 ppr_ty ctxt_prec ty@(ForAllTy _ _)
150 = getPprStyle $ \ sty ->
151 maybeParen ctxt_prec fUN_PREC $
152 sep [ ptext SLIT("forall") <+> pp_tyvars sty <> ptext SLIT("."),
157 (tyvars, theta, tau) = tcSplitSigmaTy ty
159 pp_tyvars sty = sep (map pprTyVarBndr some_tyvars)
161 some_tyvars | userStyle sty && not opt_PprStyle_RawTypes
162 = filter (not . isUTyVar) tyvars -- hide uvars from user
167 ppr_theta theta = pprTheta theta <+> ptext SLIT("=>")
170 ppr_ty ctxt_prec (FunTy ty1 ty2)
171 -- we don't want to lose usage annotations or synonyms,
172 -- so we mustn't use splitFunTys here.
173 = maybeParen ctxt_prec fUN_PREC $
174 sep [ ppr_ty fUN_PREC ty1
175 , ptext arrow <+> ppr_ty tOP_PREC ty2
177 where arrow | isPredTy ty1 = SLIT("=>")
178 | otherwise = SLIT("->")
180 ppr_ty ctxt_prec (AppTy ty1 ty2)
181 = maybeParen ctxt_prec tYCON_PREC $
182 ppr_ty fUN_PREC ty1 <+> ppr_ty tYCON_PREC ty2
184 ppr_ty ctxt_prec (UsageTy u ty)
185 = maybeParen ctxt_prec tYCON_PREC $
186 ptext SLIT("__u") <+> ppr_ty tYCON_PREC u
187 <+> ppr_ty tYCON_PREC ty
188 -- fUN_PREC would be logical for u, but it yields a reduce/reduce conflict with AppTy
190 ppr_ty ctxt_prec (NoteTy (SynNote ty) expansion)
191 = ppr_ty ctxt_prec ty
192 -- = ppr_ty ctxt_prec expansion -- if we don't want to see syntys
194 ppr_ty ctxt_prec (NoteTy (FTVNote _) ty) = ppr_ty ctxt_prec ty
196 ppr_ty ctxt_prec (SourceTy (NType tc tys))
197 = ppr_tc_app ctxt_prec tc tys
199 ppr_ty ctxt_prec (SourceTy pred) = braces (pprPred pred)
201 ppr_tc_app ctxt_prec tc [] = ppr tc
202 ppr_tc_app ctxt_prec tc tys = maybeParen ctxt_prec tYCON_PREC
203 (sep [ppr tc, nest 4 (sep (map (ppr_ty tYCON_PREC) tys))])
207 %************************************************************************
209 \subsection[TyVar]{@TyVar@}
211 %************************************************************************
213 We print type-variable binders with their kinds in interface files,
214 and when in debug mode.
217 pprTyVarBndr :: TyVar -> SDoc
219 = getPprStyle $ \ sty ->
220 if (ifaceStyle sty && not (kind `eqKind` liftedTypeKind)) || debugStyle sty then
221 hsep [ppr tyvar, dcolon, pprParendKind kind]
222 -- See comments with ppDcolon in PprCore.lhs
226 kind = tyVarKind tyvar
228 pprTyVarBndrs tyvars = hsep (map pprTyVarBndr tyvars)
232 %************************************************************************
234 \subsection{Mumbo jumbo}
236 %************************************************************************
238 Grab a name for the type. This is used to determine the type
239 description for profiling.
242 getTyDescription :: Type -> String
245 = case (tcSplitSigmaTy ty) of { (_, _, tau_ty) ->
248 AppTy fun _ -> getTyDescription fun
249 FunTy _ res -> '-' : '>' : fun_result res
250 TyConApp tycon _ -> getOccString tycon
251 NoteTy (FTVNote _) ty -> getTyDescription ty
252 NoteTy (SynNote ty1) _ -> getTyDescription ty1
253 SourceTy sty -> getSourceTyDescription sty
254 ForAllTy _ ty -> getTyDescription ty
257 fun_result (FunTy _ res) = '>' : fun_result res
258 fun_result other = getTyDescription other
260 getSourceTyDescription (ClassP cl tys) = getOccString cl
261 getSourceTyDescription (NType tc tys) = getOccString tc
262 getSourceTyDescription (IParam id ty) = getOccString id
267 showTypeCategory :: Type -> Char
269 {C,I,F,D} char, int, float, double
271 S other single-constructor type
272 {c,i,f,d} unboxed ditto
274 s *unpacked" single-cons...
280 + dictionary, unless it's a ...
283 M other (multi-constructor) data-con type
285 - reserved for others to mark as "uninteresting"
291 case tcSplitTyConApp_maybe ty of
292 Nothing -> if maybeToBool (tcSplitFunTy_maybe ty)
297 let utc = getUnique tycon in
298 if utc == charDataConKey then 'C'
299 else if utc == intDataConKey then 'I'
300 else if utc == floatDataConKey then 'F'
301 else if utc == doubleDataConKey then 'D'
302 else if utc == smallIntegerDataConKey ||
303 utc == largeIntegerDataConKey then 'J'
304 else if utc == charPrimTyConKey then 'c'
305 else if (utc == intPrimTyConKey || utc == wordPrimTyConKey
306 || utc == addrPrimTyConKey) then 'i'
307 else if utc == floatPrimTyConKey then 'f'
308 else if utc == doublePrimTyConKey then 'd'
309 else if isPrimTyCon tycon {- array, we hope -} then 'A' -- Bogus
310 else if isEnumerationTyCon tycon then 'E'
311 else if isTupleTyCon tycon then 'T'
312 else if maybeToBool (maybeTyConSingleCon tycon) then 'S'
313 else if utc == listTyConKey then 'L'
314 else 'M' -- oh, well...