2 % (c) The AQUA Project, Glasgow University, 1996-1998
4 \section[PprType]{Printing Types, TyVars, Classes, TyCons}
8 pprKind, pprParendKind,
9 pprType, pprParendType,
10 pprConstraint, pprPred, pprTheta,
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, boxedTypeKind ) -- friend
22 import Type ( PredType(..), ThetaType,
24 splitForAllTys, splitSigmaTy, splitRhoTy,
25 isDictTy, splitTyConApp_maybe, splitFunTy_maybe,
28 import Var ( TyVar, tyVarKind )
29 import TyCon ( TyCon, isPrimTyCon, isTupleTyCon, tupleTyConBoxity,
30 maybeTyConSingleCon, isEnumerationTyCon,
33 import Class ( Class )
36 import CmdLineOpts ( opt_PprStyle_RawTypes )
37 import Maybes ( maybeToBool )
38 import Name ( getOccString, getOccName )
41 import Unique ( Uniquable(..) )
42 import BasicTypes ( tupleParens )
43 import PrelNames -- quite a few *Keys
46 %************************************************************************
48 \subsection{The external interface}
50 %************************************************************************
52 @pprType@ is the standard @Type@ printer; the overloaded @ppr@ function is
53 defined to use this. @pprParendType@ is the same, except it puts
54 parens around the type, except for the atomic cases. @pprParendType@
55 works just by setting the initial context precedence very high.
58 pprType, pprParendType :: Type -> SDoc
59 pprType ty = ppr_ty pprTyEnv tOP_PREC ty
60 pprParendType ty = ppr_ty pprTyEnv tYCON_PREC ty
62 pprKind, pprParendKind :: Kind -> SDoc
64 pprParendKind = pprParendType
66 pprPred :: PredType -> SDoc
67 pprPred (Class clas tys) = pprConstraint clas tys
68 pprPred (IParam n ty) = hsep [ptext SLIT("?") <> ppr n,
69 ptext SLIT("::"), ppr ty]
71 pprConstraint :: Class -> [Type] -> SDoc
72 pprConstraint clas tys = ppr clas <+> hsep (map pprParendType tys)
74 pprTheta :: ThetaType -> SDoc
75 pprTheta theta = parens (hsep (punctuate comma (map pprPred theta)))
77 instance Outputable Type where
80 instance Outputable PredType where
85 %************************************************************************
87 \subsection{Pretty printing}
89 %************************************************************************
93 @ppr_ty@ takes an @Int@ that is the precedence of the context.
94 The precedence levels are:
96 \item[tOP_PREC] No parens required.
97 \item[fUN_PREC] Left hand argument of a function arrow.
98 \item[tYCON_PREC] Argument of a type constructor.
103 tOP_PREC = (0 :: Int) -- type in ParseIface.y
104 fUN_PREC = (1 :: Int) -- btype in ParseIface.y
105 tYCON_PREC = (2 :: Int) -- atype in ParseIface.y
107 maybeParen ctxt_prec inner_prec pretty
108 | ctxt_prec < inner_prec = pretty
109 | otherwise = parens pretty
113 ppr_ty :: PprEnv TyVar -> Int -> Type -> SDoc
114 ppr_ty env ctxt_prec (TyVarTy tyvar)
117 ppr_ty env ctxt_prec ty@(TyConApp tycon tys)
118 -- KIND CASE; it's of the form (Type x)
119 | tycon `hasKey` typeConKey && n_tys == 1
120 = -- For kinds, print (Type x) as just x if x is a
121 -- type constructor (must be Boxed, Unboxed, AnyBox)
122 -- Otherwise print as (Type x)
124 TyConApp bx [] -> ppr (getOccName bx) -- Always unqualified
125 other -> maybeParen ctxt_prec tYCON_PREC
126 (sep [ppr tycon, nest 4 tys_w_spaces])
129 | (tycon `hasKey` usOnceTyConKey || tycon `hasKey` usManyTyConKey) && n_tys == 0
130 = -- For usages (! and .), always print bare OccName, without pkg/mod/uniq
131 ppr (getOccName (tyConName tycon))
133 -- TUPLE CASE (boxed and unboxed)
135 && length tys == tyConArity tycon -- no magic if partially applied
136 = tupleParens (tupleTyConBoxity tycon) tys_w_commas
139 | tycon `hasKey` listTyConKey && n_tys == 1
140 = brackets (ppr_ty env tOP_PREC ty1)
142 -- DICTIONARY CASE, prints {C a}
143 -- This means that instance decls come out looking right in interfaces
144 -- and that in turn means they get "gated" correctly when being slurped in
145 | maybeToBool maybe_pred
146 = braces (ppr_pred env pred)
148 -- NO-ARGUMENT CASE (=> no parens)
154 = maybeParen ctxt_prec tYCON_PREC (sep [ppr tycon, nest 4 tys_w_spaces])
159 Just pred = maybe_pred
160 maybe_pred = splitPredTy_maybe ty -- Checks class and arity
161 tys_w_commas = sep (punctuate comma (map (ppr_ty env tOP_PREC) tys))
162 tys_w_spaces = sep (map (ppr_ty env tYCON_PREC) tys)
166 ppr_ty env ctxt_prec ty@(ForAllTy _ _)
167 = getPprStyle $ \ sty ->
168 maybeParen ctxt_prec fUN_PREC $
169 sep [ ptext SLIT("forall") <+> pp_tyvars sty <> ptext SLIT("."),
171 ppr_ty env tOP_PREC tau
174 (tyvars, rho) = splitForAllTys ty
175 (theta, tau) = splitRhoTy rho
177 pp_tyvars sty = hsep (map (pBndr env LambdaBind) some_tyvars)
179 some_tyvars | userStyle sty && not opt_PprStyle_RawTypes
180 = filter (not . isUTyVar) tyvars -- hide uvars from user
185 ppr_theta theta = parens (hsep (punctuate comma (map (ppr_pred env) theta)))
189 ppr_ty env ctxt_prec (FunTy ty1 ty2)
190 -- we don't want to lose usage annotations or synonyms,
191 -- so we mustn't use splitFunTys here.
192 = maybeParen ctxt_prec fUN_PREC $
193 sep [ ppr_ty env fUN_PREC ty1
194 , ptext SLIT("->") <+> ppr_ty env tOP_PREC ty2
197 ppr_ty env ctxt_prec (AppTy ty1 ty2)
198 = maybeParen ctxt_prec tYCON_PREC $
199 ppr_ty env fUN_PREC ty1 <+> ppr_ty env tYCON_PREC ty2
201 ppr_ty env ctxt_prec (UsageTy u ty)
202 = maybeParen ctxt_prec tYCON_PREC $
203 ptext SLIT("__u") <+> ppr_ty env tYCON_PREC u
204 <+> ppr_ty env tYCON_PREC ty
205 -- fUN_PREC would be logical for u, but it yields a reduce/reduce conflict with AppTy
207 ppr_ty env ctxt_prec (NoteTy (SynNote ty) expansion)
208 = ppr_ty env ctxt_prec ty
209 -- = ppr_ty env ctxt_prec expansion -- if we don't want to see syntys
211 ppr_ty env ctxt_prec (NoteTy (FTVNote _) ty) = ppr_ty env ctxt_prec ty
213 ppr_ty env ctxt_prec (PredTy p) = braces (ppr_pred env p)
215 ppr_pred env (Class clas tys) = ppr clas <+>
216 hsep (map (ppr_ty env tYCON_PREC) tys)
217 ppr_pred env (IParam n ty) = hsep [char '?' <> ppr n, text "::",
218 ppr_ty env tYCON_PREC ty]
222 pprTyEnv = initPprEnv b (Just ppr) b (Just (\site -> pprTyVarBndr)) b
224 b = panic "PprType:init_ppr_env"
228 %************************************************************************
230 \subsection[TyVar]{@TyVar@}
232 %************************************************************************
234 We print type-variable binders with their kinds in interface files,
235 and when in debug mode.
239 = getPprStyle $ \ sty ->
240 if (ifaceStyle sty && kind /= boxedTypeKind) || debugStyle sty then
241 hsep [ppr tyvar, dcolon, pprParendKind kind]
242 -- See comments with ppDcolon in PprCore.lhs
246 kind = tyVarKind tyvar
248 pprTyVarBndrs tyvars = hsep (map pprTyVarBndr tyvars)
252 %************************************************************************
254 \subsection{Mumbo jumbo}
256 %************************************************************************
258 Grab a name for the type. This is used to determine the type
259 description for profiling.
262 getTyDescription :: Type -> String
265 = case (splitSigmaTy ty) of { (_, _, tau_ty) ->
268 AppTy fun _ -> getTyDescription fun
269 FunTy _ res -> '-' : '>' : fun_result res
270 TyConApp tycon _ -> getOccString tycon
271 NoteTy (FTVNote _) ty -> getTyDescription ty
272 NoteTy (SynNote ty1) _ -> getTyDescription ty1
273 PredTy p -> getTyDescription (predRepTy p)
274 ForAllTy _ ty -> getTyDescription ty
277 fun_result (FunTy _ res) = '>' : fun_result res
278 fun_result other = getTyDescription other
283 showTypeCategory :: Type -> Char
285 {C,I,F,D} char, int, float, double
287 S other single-constructor type
288 {c,i,f,d} unboxed ditto
290 s *unpacked" single-cons...
296 + dictionary, unless it's a ...
299 M other (multi-constructor) data-con type
301 - reserved for others to mark as "uninteresting"
307 case splitTyConApp_maybe ty of
308 Nothing -> if maybeToBool (splitFunTy_maybe ty)
313 let utc = getUnique tycon in
314 if utc == charDataConKey then 'C'
315 else if utc == intDataConKey then 'I'
316 else if utc == floatDataConKey then 'F'
317 else if utc == doubleDataConKey then 'D'
318 else if utc == smallIntegerDataConKey ||
319 utc == largeIntegerDataConKey then 'J'
320 else if utc == charPrimTyConKey then 'c'
321 else if (utc == intPrimTyConKey || utc == wordPrimTyConKey
322 || utc == addrPrimTyConKey) then 'i'
323 else if utc == floatPrimTyConKey then 'f'
324 else if utc == doublePrimTyConKey then 'd'
325 else if isPrimTyCon tycon {- array, we hope -} then 'A'
326 else if isEnumerationTyCon tycon then 'E'
327 else if isTupleTyCon tycon then 'T'
328 else if maybeToBool (maybeTyConSingleCon tycon) then 'S'
329 else if utc == listTyConKey then 'L'
330 else 'M' -- oh, well...