%
% (c) The University of Glasgow 2006
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
HsTypes: Abstract syntax: user-defined types
\begin{code}
module HsTypes (
HsType(..), LHsType,
HsTyVarBndr(..), LHsTyVarBndr,
HsExplicitFlag(..),
HsContext, LHsContext,
HsPred(..), LHsPred,
HsQuasiQuote(..),
LBangType, BangType, HsBang(..),
getBangType, getBangStrictness,
ConDeclField(..), pprConDeclFields,
mkExplicitHsForAllTy, mkImplicitHsForAllTy, hsExplicitTvs,
hsTyVarName, hsTyVarNames, replaceTyVarName,
hsTyVarKind, hsTyVarNameKind,
hsLTyVarName, hsLTyVarNames, hsLTyVarLocName, hsLTyVarLocNames,
splitHsInstDeclTy, splitHsFunType,
PostTcType, placeHolderType, PostTcKind, placeHolderKind,
pprParendHsType, pprHsForAll, pprHsContext, ppr_hs_context,
) where
import HsExpr ( HsSplice, pprSplice )
import NameSet( FreeVars )
import Type
import HsDoc
import BasicTypes
import SrcLoc
import StaticFlags
import Outputable
import FastString
import Data.Data
\end{code}
%************************************************************************
%* *
\subsection{Annotating the syntax}
%* *
%************************************************************************
\begin{code}
type PostTcKind = Kind
type PostTcType = Type
placeHolderType :: PostTcType
placeHolderType = panic "Evaluated the place holder for a PostTcType"
placeHolderKind :: PostTcKind
placeHolderKind = panic "Evaluated the place holder for a PostTcKind"
\end{code}
%************************************************************************
%* *
Quasi quotes; used in types and elsewhere
%* *
%************************************************************************
\begin{code}
data HsQuasiQuote id = HsQuasiQuote
id
SrcSpan
FastString
deriving (Data, Typeable)
instance OutputableBndr id => Outputable (HsQuasiQuote id) where
ppr = ppr_qq
ppr_qq :: OutputableBndr id => HsQuasiQuote id -> SDoc
ppr_qq (HsQuasiQuote quoter _ quote) =
char '[' <> ppr quoter <> ptext (sLit "|") <>
ppr quote <> ptext (sLit "|]")
\end{code}
%************************************************************************
%* *
\subsection{Bang annotations}
%* *
%************************************************************************
\begin{code}
type LBangType name = Located (BangType name)
type BangType name = HsType name
getBangType :: LHsType a -> LHsType a
getBangType (L _ (HsBangTy _ ty)) = ty
getBangType ty = ty
getBangStrictness :: LHsType a -> HsBang
getBangStrictness (L _ (HsBangTy s _)) = s
getBangStrictness _ = HsNoBang
\end{code}
%************************************************************************
%* *
\subsection{Data types}
%* *
%************************************************************************
This is the syntax for types as seen in type signatures.
\begin{code}
type LHsContext name = Located (HsContext name)
type HsContext name = [LHsPred name]
type LHsPred name = Located (HsPred name)
data HsPred name = HsClassP name [LHsType name]
| HsEqualP (LHsType name) (LHsType name)
| HsIParam (IPName name) (LHsType name)
deriving (Data, Typeable)
type LHsType name = Located (HsType name)
data HsType name
= HsForAllTy HsExplicitFlag
[LHsTyVarBndr name]
(LHsContext name)
(LHsType name)
| HsTyVar name
| HsAppTy (LHsType name)
(LHsType name)
| HsFunTy (LHsType name)
(LHsType name)
| HsListTy (LHsType name)
| HsPArrTy (LHsType name)
| HsTupleTy Boxity
[LHsType name]
| HsOpTy (LHsType name) (Located name) (LHsType name)
| HsParTy (LHsType name)
| HsNumTy Integer
| HsPredTy (HsPred name)
| HsKindSig (LHsType name)
Kind
| HsQuasiQuoteTy (HsQuasiQuote name)
| HsSpliceTy (HsSplice name)
FreeVars
PostTcKind
| HsDocTy (LHsType name) LHsDocString
| HsBangTy HsBang (LHsType name)
| HsRecTy [ConDeclField name]
| HsCoreTy Type
deriving (Data, Typeable)
data HsExplicitFlag = Explicit | Implicit deriving (Data, Typeable)
data ConDeclField name
= ConDeclField { cd_fld_name :: Located name,
cd_fld_type :: LBangType name,
cd_fld_doc :: Maybe LHsDocString }
deriving (Data, Typeable)
mkImplicitHsForAllTy :: LHsContext name -> LHsType name -> HsType name
mkExplicitHsForAllTy :: [LHsTyVarBndr name] -> LHsContext name -> LHsType name -> HsType name
mkImplicitHsForAllTy ctxt ty = mkHsForAllTy Implicit [] ctxt ty
mkExplicitHsForAllTy tvs ctxt ty = mkHsForAllTy Explicit tvs ctxt ty
mkHsForAllTy :: HsExplicitFlag -> [LHsTyVarBndr name] -> LHsContext name -> LHsType name -> HsType name
mkHsForAllTy exp tvs (L _ []) ty = mk_forall_ty exp tvs ty
mkHsForAllTy exp tvs ctxt ty = HsForAllTy exp tvs ctxt ty
mk_forall_ty :: HsExplicitFlag -> [LHsTyVarBndr name] -> LHsType name -> HsType name
mk_forall_ty exp tvs (L _ (HsParTy ty)) = mk_forall_ty exp tvs ty
mk_forall_ty exp1 tvs1 (L _ (HsForAllTy exp2 tvs2 ctxt ty)) = mkHsForAllTy (exp1 `plus` exp2) (tvs1 ++ tvs2) ctxt ty
mk_forall_ty exp tvs ty = HsForAllTy exp tvs (L noSrcSpan []) ty
plus :: HsExplicitFlag -> HsExplicitFlag -> HsExplicitFlag
Implicit `plus` Implicit = Implicit
_ `plus` _ = Explicit
hsExplicitTvs :: LHsType name -> [name]
hsExplicitTvs (L _ (HsForAllTy Explicit tvs _ _)) = hsLTyVarNames tvs
hsExplicitTvs _ = []
type LHsTyVarBndr name = Located (HsTyVarBndr name)
data HsTyVarBndr name
= UserTyVar
name
PostTcKind
| KindedTyVar
name
Kind
deriving (Data, Typeable)
hsTyVarName :: HsTyVarBndr name -> name
hsTyVarName (UserTyVar n _) = n
hsTyVarName (KindedTyVar n _) = n
hsTyVarKind :: HsTyVarBndr name -> Kind
hsTyVarKind (UserTyVar _ k) = k
hsTyVarKind (KindedTyVar _ k) = k
hsTyVarNameKind :: HsTyVarBndr name -> (name, Kind)
hsTyVarNameKind (UserTyVar n k) = (n,k)
hsTyVarNameKind (KindedTyVar n k) = (n,k)
hsLTyVarName :: LHsTyVarBndr name -> name
hsLTyVarName = hsTyVarName . unLoc
hsTyVarNames :: [HsTyVarBndr name] -> [name]
hsTyVarNames tvs = map hsTyVarName tvs
hsLTyVarNames :: [LHsTyVarBndr name] -> [name]
hsLTyVarNames = map hsLTyVarName
hsLTyVarLocName :: LHsTyVarBndr name -> Located name
hsLTyVarLocName = fmap hsTyVarName
hsLTyVarLocNames :: [LHsTyVarBndr name] -> [Located name]
hsLTyVarLocNames = map hsLTyVarLocName
replaceTyVarName :: HsTyVarBndr name1 -> name2 -> HsTyVarBndr name2
replaceTyVarName (UserTyVar _ k) n' = UserTyVar n' k
replaceTyVarName (KindedTyVar _ k) n' = KindedTyVar n' k
\end{code}
\begin{code}
splitHsInstDeclTy
:: OutputableBndr name
=> HsType name
-> ([LHsTyVarBndr name], HsContext name, name, [LHsType name])
splitHsInstDeclTy inst_ty
= case inst_ty of
HsParTy (L _ ty) -> splitHsInstDeclTy ty
HsForAllTy _ tvs cxt (L _ ty) -> split_tau tvs (unLoc cxt) ty
other -> split_tau [] [] other
where
split_tau tvs cxt (HsPredTy (HsClassP cls tys)) = (tvs, cxt, cls, tys)
split_tau tvs cxt (HsParTy (L _ ty)) = split_tau tvs cxt ty
split_tau _ _ _ = pprPanic "splitHsInstDeclTy" (ppr inst_ty)
splitHsFunType :: LHsType name -> ([LHsType name], LHsType name)
splitHsFunType (L _ (HsFunTy x y)) = (x:args, res)
where
(args, res) = splitHsFunType y
splitHsFunType (L _ (HsParTy ty)) = splitHsFunType ty
splitHsFunType other = ([], other)
\end{code}
%************************************************************************
%* *
\subsection{Pretty printing}
%* *
%************************************************************************
\begin{code}
instance (OutputableBndr name) => Outputable (HsType name) where
ppr ty = pprHsType ty
instance (Outputable name) => Outputable (HsTyVarBndr name) where
ppr (UserTyVar name _) = ppr name
ppr (KindedTyVar name kind) = hsep [ppr name, dcolon, pprParendKind kind]
instance OutputableBndr name => Outputable (HsPred name) where
ppr (HsClassP clas tys) = ppr clas <+> hsep (map pprLHsType tys)
ppr (HsEqualP t1 t2) = hsep [pprLHsType t1, ptext (sLit "~"),
pprLHsType t2]
ppr (HsIParam n ty) = hsep [ppr n, dcolon, ppr ty]
pprLHsType :: OutputableBndr name => LHsType name -> SDoc
pprLHsType = pprParendHsType . unLoc
pprHsForAll :: OutputableBndr name => HsExplicitFlag -> [LHsTyVarBndr name] -> LHsContext name -> SDoc
pprHsForAll exp tvs cxt
| show_forall = forall_part <+> pprHsContext (unLoc cxt)
| otherwise = pprHsContext (unLoc cxt)
where
show_forall = opt_PprStyle_Debug
|| (not (null tvs) && is_explicit)
is_explicit = case exp of {Explicit -> True; Implicit -> False}
forall_part = ptext (sLit "forall") <+> interppSP tvs <> dot
pprHsContext :: (OutputableBndr name) => HsContext name -> SDoc
pprHsContext [] = empty
pprHsContext [L _ pred]
| noParenHsPred pred = ppr pred <+> darrow
pprHsContext cxt = ppr_hs_context cxt <+> darrow
noParenHsPred :: HsPred name -> Bool
noParenHsPred (HsClassP {}) = True
noParenHsPred (HsEqualP {}) = True
noParenHsPred (HsIParam {}) = False
ppr_hs_context :: (OutputableBndr name) => HsContext name -> SDoc
ppr_hs_context [] = empty
ppr_hs_context cxt = parens (interpp'SP cxt)
pprConDeclFields :: OutputableBndr name => [ConDeclField name] -> SDoc
pprConDeclFields fields = braces (sep (punctuate comma (map ppr_fld fields)))
where
ppr_fld (ConDeclField { cd_fld_name = n, cd_fld_type = ty,
cd_fld_doc = doc })
= ppr n <+> dcolon <+> ppr ty <+> ppr_mbDoc doc
\end{code}
Note [Printing KindedTyVars]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Trac #3830 reminded me that we should really only print the kind
signature on a KindedTyVar if the kind signature was put there by the
programmer. During kind inference GHC now adds a PostTcKind to UserTyVars,
rather than converting to KindedTyVars as before.
(As it happens, the message in #3830 comes out a different way now,
and the problem doesn't show up; but having the flag on a KindedTyVar
seems like the Right Thing anyway.)
\begin{code}
pREC_TOP, pREC_FUN, pREC_OP, pREC_CON :: Int
pREC_TOP = 0
pREC_FUN = 1
pREC_OP = 2
pREC_CON = 3
maybeParen :: Int
-> Int
-> SDoc -> SDoc
maybeParen ctxt_prec op_prec p | ctxt_prec >= op_prec = parens p
| otherwise = p
pprHsType, pprParendHsType :: (OutputableBndr name) => HsType name -> SDoc
pprHsType ty = getPprStyle $ \sty -> ppr_mono_ty pREC_TOP (prepare sty ty)
pprParendHsType ty = ppr_mono_ty pREC_CON ty
prepare :: PprStyle -> HsType name -> HsType name
prepare sty (HsParTy ty) = prepare sty (unLoc ty)
prepare _ ty = ty
ppr_mono_lty :: (OutputableBndr name) => Int -> LHsType name -> SDoc
ppr_mono_lty ctxt_prec ty = ppr_mono_ty ctxt_prec (unLoc ty)
ppr_mono_ty :: (OutputableBndr name) => Int -> HsType name -> SDoc
ppr_mono_ty ctxt_prec (HsForAllTy exp tvs ctxt ty)
= maybeParen ctxt_prec pREC_FUN $
sep [pprHsForAll exp tvs ctxt, ppr_mono_lty pREC_TOP ty]
ppr_mono_ty _ (HsBangTy b ty) = ppr b <> ppr ty
ppr_mono_ty _ (HsQuasiQuoteTy qq) = ppr qq
ppr_mono_ty _ (HsRecTy flds) = pprConDeclFields flds
ppr_mono_ty _ (HsTyVar name) = ppr name
ppr_mono_ty prec (HsFunTy ty1 ty2) = ppr_fun_ty prec ty1 ty2
ppr_mono_ty _ (HsTupleTy con tys) = tupleParens con (interpp'SP tys)
ppr_mono_ty _ (HsKindSig ty kind) = parens (ppr_mono_lty pREC_TOP ty <+> dcolon <+> pprKind kind)
ppr_mono_ty _ (HsListTy ty) = brackets (ppr_mono_lty pREC_TOP ty)
ppr_mono_ty _ (HsPArrTy ty) = pabrackets (ppr_mono_lty pREC_TOP ty)
ppr_mono_ty _ (HsPredTy pred) = ppr pred
ppr_mono_ty _ (HsNumTy n) = integer n
ppr_mono_ty _ (HsSpliceTy s _ _) = pprSplice s
ppr_mono_ty _ (HsCoreTy ty) = ppr ty
ppr_mono_ty ctxt_prec (HsAppTy fun_ty arg_ty)
= maybeParen ctxt_prec pREC_CON $
hsep [ppr_mono_lty pREC_FUN fun_ty, ppr_mono_lty pREC_CON arg_ty]
ppr_mono_ty ctxt_prec (HsOpTy ty1 op ty2)
= maybeParen ctxt_prec pREC_OP $
ppr_mono_lty pREC_OP ty1 <+> ppr op <+> ppr_mono_lty pREC_OP ty2
ppr_mono_ty _ (HsParTy ty)
= parens (ppr_mono_lty pREC_TOP ty)
ppr_mono_ty ctxt_prec (HsDocTy ty doc)
= maybeParen ctxt_prec pREC_OP $
ppr_mono_lty pREC_OP ty <+> ppr (unLoc doc)
ppr_fun_ty :: (OutputableBndr name) => Int -> LHsType name -> LHsType name -> SDoc
ppr_fun_ty ctxt_prec ty1 ty2
= let p1 = ppr_mono_lty pREC_FUN ty1
p2 = ppr_mono_lty pREC_TOP ty2
in
maybeParen ctxt_prec pREC_FUN $
sep [p1, ptext (sLit "->") <+> p2]
pabrackets :: SDoc -> SDoc
pabrackets p = ptext (sLit "[:") <> p <> ptext (sLit ":]")
\end{code}