module Language.Haskell.TH.Ppr where
import Text.PrettyPrint.HughesPJ (render)
import Language.Haskell.TH.PprLib
import Language.Haskell.TH.Syntax
import Data.Char ( toLower )
nestDepth :: Int
nestDepth = 4
type Precedence = Int
appPrec, opPrec, noPrec :: Precedence
appPrec = 2
opPrec = 1
noPrec = 0
parensIf :: Bool -> Doc -> Doc
parensIf True d = parens d
parensIf False d = d
pprint :: Ppr a => a -> String
pprint x = render $ to_HPJ_Doc $ ppr x
class Ppr a where
ppr :: a -> Doc
ppr_list :: [a] -> Doc
ppr_list = vcat . map ppr
instance Ppr a => Ppr [a] where
ppr x = ppr_list x
instance Ppr Name where
ppr v = pprName v
instance Ppr Info where
ppr (ClassI d is) = ppr d $$ vcat (map ppr is)
ppr (TyConI d) = ppr d
ppr (PrimTyConI name arity is_unlifted)
= text "Primitive"
<+> (if is_unlifted then text "unlifted" else empty)
<+> text "type construtor" <+> quotes (ppr name)
<+> parens (text "arity" <+> int arity)
ppr (ClassOpI v ty cls fix)
= text "Class op from" <+> ppr cls <> colon <+>
vcat [ppr_sig v ty, pprFixity v fix]
ppr (DataConI v ty tc fix)
= text "Constructor from" <+> ppr tc <> colon <+>
vcat [ppr_sig v ty, pprFixity v fix]
ppr (TyVarI v ty)
= text "Type variable" <+> ppr v <+> equals <+> ppr ty
ppr (VarI v ty mb_d fix)
= vcat [ppr_sig v ty, pprFixity v fix,
case mb_d of { Nothing -> empty; Just d -> ppr d }]
instance Ppr ClassInstance where
ppr (ClassInstance { ci_dfun = _dfun,
ci_tvs = _tvs,
ci_cxt = cxt,
ci_cls = cls,
ci_tys = tys })
= text "instance" <+> pprCxt cxt
<+> ppr cls <+> sep (map pprParendType tys)
ppr_sig :: Name -> Type -> Doc
ppr_sig v ty = ppr v <+> text "::" <+> ppr ty
pprFixity :: Name -> Fixity -> Doc
pprFixity _ f | f == defaultFixity = empty
pprFixity v (Fixity i d) = ppr_fix d <+> int i <+> ppr v
where ppr_fix InfixR = text "infixr"
ppr_fix InfixL = text "infixl"
ppr_fix InfixN = text "infix"
instance Ppr Exp where
ppr = pprExp noPrec
pprInfixExp :: Exp -> Doc
pprInfixExp (VarE v) = pprName' Infix v
pprInfixExp (ConE v) = pprName' Infix v
pprInfixExp _ = error "Attempt to pretty-print non-variable or constructor in infix context!"
pprExp :: Precedence -> Exp -> Doc
pprExp _ (VarE v) = pprName' Applied v
pprExp _ (ConE c) = pprName' Applied c
pprExp i (LitE l) = pprLit i l
pprExp i (AppE e1 e2) = parensIf (i >= appPrec) $ pprExp opPrec e1
<+> pprExp appPrec e2
pprExp i (InfixE (Just e1) op (Just e2))
= parensIf (i >= opPrec) $ pprExp opPrec e1
<+> pprInfixExp op
<+> pprExp opPrec e2
pprExp _ (InfixE me1 op me2) = parens $ pprMaybeExp noPrec me1
<+> pprInfixExp op
<+> pprMaybeExp noPrec me2
pprExp i (LamE ps e) = parensIf (i > noPrec) $ char '\\' <> hsep (map (pprPat appPrec) ps)
<+> text "->" <+> ppr e
pprExp _ (TupE es) = parens $ sep $ punctuate comma $ map ppr es
pprExp i (CondE guard true false)
= parensIf (i > noPrec) $ sep [text "if" <+> ppr guard,
nest 1 $ text "then" <+> ppr true,
nest 1 $ text "else" <+> ppr false]
pprExp i (LetE ds e) = parensIf (i > noPrec) $ text "let" <+> ppr ds
$$ text " in" <+> ppr e
pprExp i (CaseE e ms)
= parensIf (i > noPrec) $ text "case" <+> ppr e <+> text "of"
$$ nest nestDepth (ppr ms)
pprExp i (DoE ss) = parensIf (i > noPrec) $ text "do" <+> ppr ss
pprExp _ (CompE []) = error "Can't happen: pprExp (CompExp [])"
pprExp _ (CompE ss) = text "[" <> ppr s
<+> text "|"
<+> (sep $ punctuate comma $ map ppr ss')
<> text "]"
where s = last ss
ss' = init ss
pprExp _ (ArithSeqE d) = ppr d
pprExp _ (ListE es) = brackets $ sep $ punctuate comma $ map ppr es
pprExp i (SigE e t) = parensIf (i > noPrec) $ ppr e <+> text "::" <+> ppr t
pprExp _ (RecConE nm fs) = ppr nm <> braces (pprFields fs)
pprExp _ (RecUpdE e fs) = pprExp appPrec e <> braces (pprFields fs)
pprFields :: [(Name,Exp)] -> Doc
pprFields = sep . punctuate comma . map (\(s,e) -> ppr s <+> equals <+> ppr e)
pprMaybeExp :: Precedence -> Maybe Exp -> Doc
pprMaybeExp _ Nothing = empty
pprMaybeExp i (Just e) = pprExp i e
instance Ppr Stmt where
ppr (BindS p e) = ppr p <+> text "<-" <+> ppr e
ppr (LetS ds) = text "let" <+> ppr ds
ppr (NoBindS e) = ppr e
ppr (ParS sss) = sep $ punctuate (text "|")
$ map (sep . punctuate comma . map ppr) sss
instance Ppr Match where
ppr (Match p rhs ds) = ppr p <+> pprBody False rhs
$$ where_clause ds
pprBody :: Bool -> Body -> Doc
pprBody eq (GuardedB xs) = nest nestDepth $ vcat $ map do_guard xs
where eqd = if eq then text "=" else text "->"
do_guard (NormalG g, e) = text "|" <+> ppr g <+> eqd <+> ppr e
do_guard (PatG ss, e) = text "|" <+> vcat (map ppr ss)
$$ nest nestDepth (eqd <+> ppr e)
pprBody eq (NormalB e) = (if eq then text "=" else text "->") <+> ppr e
pprLit :: Precedence -> Lit -> Doc
pprLit i (IntPrimL x) = parensIf (i > noPrec && x < 0)
(integer x <> char '#')
pprLit _ (WordPrimL x) = integer x <> text "##"
pprLit i (FloatPrimL x) = parensIf (i > noPrec && x < 0)
(float (fromRational x) <> char '#')
pprLit i (DoublePrimL x) = parensIf (i > noPrec && x < 0)
(double (fromRational x) <> text "##")
pprLit i (IntegerL x) = parensIf (i > noPrec && x < 0) (integer x)
pprLit _ (CharL c) = text (show c)
pprLit _ (StringL s) = text (show s)
pprLit _ (StringPrimL s) = text (show s) <> char '#'
pprLit i (RationalL rat) = parensIf (i > noPrec) $ rational rat
instance Ppr Pat where
ppr = pprPat noPrec
pprPat :: Precedence -> Pat -> Doc
pprPat i (LitP l) = pprLit i l
pprPat _ (VarP v) = pprName' Applied v
pprPat _ (TupP ps) = parens $ sep $ punctuate comma $ map ppr ps
pprPat i (ConP s ps) = parensIf (i >= appPrec) $ pprName' Applied s
<+> sep (map (pprPat appPrec) ps)
pprPat i (InfixP p1 n p2)
= parensIf (i >= opPrec) (pprPat opPrec p1 <+>
pprName' Infix n <+>
pprPat opPrec p2)
pprPat i (TildeP p) = parensIf (i > noPrec) $ char '~' <> pprPat appPrec p
pprPat i (BangP p) = parensIf (i > noPrec) $ char '!' <> pprPat appPrec p
pprPat i (AsP v p) = parensIf (i > noPrec) $ ppr v <> text "@"
<> pprPat appPrec p
pprPat _ WildP = text "_"
pprPat _ (RecP nm fs)
= parens $ ppr nm
<+> braces (sep $ punctuate comma $
map (\(s,p) -> ppr s <+> equals <+> ppr p) fs)
pprPat _ (ListP ps) = brackets $ sep $ punctuate comma $ map ppr ps
pprPat i (SigP p t) = parensIf (i > noPrec) $ ppr p <+> text "::" <+> ppr t
pprPat _ (ViewP e p) = parens $ pprExp noPrec e <+> text "->" <+> pprPat noPrec p
instance Ppr Dec where
ppr = ppr_dec True
ppr_dec :: Bool
-> Dec
-> Doc
ppr_dec _ (FunD f cs) = vcat $ map (\c -> ppr f <+> ppr c) cs
ppr_dec _ (ValD p r ds) = ppr p <+> pprBody True r
$$ where_clause ds
ppr_dec _ (TySynD t xs rhs)
= ppr_tySyn empty t (hsep (map ppr xs)) rhs
ppr_dec _ (DataD ctxt t xs cs decs)
= ppr_data empty ctxt t (hsep (map ppr xs)) cs decs
ppr_dec _ (NewtypeD ctxt t xs c decs)
= ppr_newtype empty ctxt t (sep (map ppr xs)) c decs
ppr_dec _ (ClassD ctxt c xs fds ds)
= text "class" <+> pprCxt ctxt <+> ppr c <+> hsep (map ppr xs) <+> ppr fds
$$ where_clause ds
ppr_dec _ (InstanceD ctxt i ds) = text "instance" <+> pprCxt ctxt <+> ppr i
$$ where_clause ds
ppr_dec _ (SigD f t) = ppr f <+> text "::" <+> ppr t
ppr_dec _ (ForeignD f) = ppr f
ppr_dec _ (PragmaD p) = ppr p
ppr_dec isTop (FamilyD flav tc tvs k)
= ppr flav <+> maybeFamily <+> ppr tc <+> hsep (map ppr tvs) <+> maybeKind
where
maybeFamily | isTop = text "family"
| otherwise = empty
maybeKind | (Just k') <- k = text "::" <+> ppr k'
| otherwise = empty
ppr_dec isTop (DataInstD ctxt tc tys cs decs)
= ppr_data maybeInst ctxt tc (sep (map pprParendType tys)) cs decs
where
maybeInst | isTop = text "instance"
| otherwise = empty
ppr_dec isTop (NewtypeInstD ctxt tc tys c decs)
= ppr_newtype maybeInst ctxt tc (sep (map pprParendType tys)) c decs
where
maybeInst | isTop = text "instance"
| otherwise = empty
ppr_dec isTop (TySynInstD tc tys rhs)
= ppr_tySyn maybeInst tc (sep (map pprParendType tys)) rhs
where
maybeInst | isTop = text "instance"
| otherwise = empty
ppr_data :: Doc -> Cxt -> Name -> Doc -> [Con] -> [Name] -> Doc
ppr_data maybeInst ctxt t argsDoc cs decs
= sep [text "data" <+> maybeInst
<+> pprCxt ctxt
<+> ppr t <+> argsDoc,
nest nestDepth (sep (pref $ map ppr cs)),
if null decs
then empty
else nest nestDepth
$ text "deriving"
<+> parens (hsep $ punctuate comma $ map ppr decs)]
where
pref :: [Doc] -> [Doc]
pref [] = []
pref (d:ds) = (char '=' <+> d):map (char '|' <+>) ds
ppr_newtype :: Doc -> Cxt -> Name -> Doc -> Con -> [Name] -> Doc
ppr_newtype maybeInst ctxt t argsDoc c decs
= sep [text "newtype" <+> maybeInst
<+> pprCxt ctxt
<+> ppr t <+> argsDoc,
nest 2 (char '=' <+> ppr c),
if null decs
then empty
else nest nestDepth
$ text "deriving"
<+> parens (hsep $ punctuate comma $ map ppr decs)]
ppr_tySyn :: Doc -> Name -> Doc -> Type -> Doc
ppr_tySyn maybeInst t argsDoc rhs
= text "type" <+> maybeInst <+> ppr t <+> argsDoc <+> text "=" <+> ppr rhs
instance Ppr FunDep where
ppr (FunDep xs ys) = hsep (map ppr xs) <+> text "->" <+> hsep (map ppr ys)
ppr_list [] = empty
ppr_list xs = char '|' <+> sep (punctuate (text ", ") (map ppr xs))
instance Ppr FamFlavour where
ppr DataFam = text "data"
ppr TypeFam = text "type"
instance Ppr Foreign where
ppr (ImportF callconv safety impent as typ)
= text "foreign import"
<+> showtextl callconv
<+> showtextl safety
<+> text (show impent)
<+> ppr as
<+> text "::" <+> ppr typ
ppr (ExportF callconv expent as typ)
= text "foreign export"
<+> showtextl callconv
<+> text (show expent)
<+> ppr as
<+> text "::" <+> ppr typ
instance Ppr Pragma where
ppr (InlineP n (InlineSpec inline conlike activation))
= text "{-#"
<+> (if inline then text "INLINE" else text "NOINLINE")
<+> (if conlike then text "CONLIKE" else empty)
<+> ppr_activation activation
<+> ppr n
<+> text "#-}"
ppr (SpecialiseP n ty Nothing)
= sep [ text "{-# SPECIALISE"
, ppr n <+> text "::"
, ppr ty
, text "#-}"
]
ppr (SpecialiseP n ty (Just (InlineSpec inline _conlike activation)))
= sep [ text "{-# SPECIALISE" <+>
(if inline then text "INLINE" else text "NOINLINE") <+>
ppr_activation activation
, ppr n <+> text "::"
, ppr ty
, text "#-}"
]
where
ppr_activation :: Maybe (Bool, Int) -> Doc
ppr_activation (Just (beforeFrom, i))
= brackets $ (if beforeFrom then empty else char '~') <+> int i
ppr_activation Nothing = empty
instance Ppr Clause where
ppr (Clause ps rhs ds) = hsep (map (pprPat appPrec) ps) <+> pprBody True rhs
$$ where_clause ds
instance Ppr Con where
ppr (NormalC c sts) = ppr c <+> sep (map pprStrictType sts)
ppr (RecC c vsts)
= ppr c <+> braces (sep (punctuate comma $ map pprVarStrictType vsts))
ppr (InfixC st1 c st2) = pprStrictType st1
<+> pprName' Infix c
<+> pprStrictType st2
ppr (ForallC ns ctxt con) = text "forall" <+> hsep (map ppr ns)
<+> char '.' <+> sep [pprCxt ctxt, ppr con]
pprVarStrictType :: (Name, Strict, Type) -> Doc
pprVarStrictType (v, str, t) = ppr v <+> text "::" <+> pprStrictType (str, t)
pprStrictType :: (Strict, Type) -> Doc
pprStrictType (IsStrict, t) = char '!' <> pprParendType t
pprStrictType (NotStrict, t) = pprParendType t
pprParendType :: Type -> Doc
pprParendType (VarT v) = ppr v
pprParendType (ConT c) = ppr c
pprParendType (TupleT 0) = text "()"
pprParendType (TupleT n) = parens (hcat (replicate (n1) comma))
pprParendType ArrowT = parens (text "->")
pprParendType ListT = text "[]"
pprParendType other = parens (ppr other)
instance Ppr Type where
ppr (ForallT tvars ctxt ty)
= text "forall" <+> hsep (map ppr tvars) <+> text "."
<+> sep [pprCxt ctxt, ppr ty]
ppr (SigT ty k) = ppr ty <+> text "::" <+> ppr k
ppr ty = pprTyApp (split ty)
pprTyApp :: (Type, [Type]) -> Doc
pprTyApp (ArrowT, [arg1,arg2]) = sep [pprFunArgType arg1 <+> text "->", ppr arg2]
pprTyApp (ListT, [arg]) = brackets (ppr arg)
pprTyApp (TupleT n, args)
| length args == n = parens (sep (punctuate comma (map ppr args)))
pprTyApp (fun, args) = pprParendType fun <+> sep (map pprParendType args)
pprFunArgType :: Type -> Doc
pprFunArgType ty@(ForallT {}) = parens (ppr ty)
pprFunArgType ty@((ArrowT `AppT` _) `AppT` _) = parens (ppr ty)
pprFunArgType ty@(SigT _ _) = parens (ppr ty)
pprFunArgType ty = ppr ty
split :: Type -> (Type, [Type])
split t = go t []
where go (AppT t1 t2) args = go t1 (t2:args)
go ty args = (ty, args)
instance Ppr TyVarBndr where
ppr (PlainTV nm) = ppr nm
ppr (KindedTV nm k) = parens (ppr nm <+> text "::" <+> ppr k)
instance Ppr Kind where
ppr StarK = char '*'
ppr (ArrowK k1 k2) = pprArrowArgKind k1 <+> text "->" <+> ppr k2
pprArrowArgKind :: Kind -> Doc
pprArrowArgKind k@(ArrowK _ _) = parens (ppr k)
pprArrowArgKind k = ppr k
pprCxt :: Cxt -> Doc
pprCxt [] = empty
pprCxt [t] = ppr t <+> text "=>"
pprCxt ts = parens (sep $ punctuate comma $ map ppr ts) <+> text "=>"
instance Ppr Pred where
ppr (ClassP cla tys) = ppr cla <+> sep (map pprParendType tys)
ppr (EqualP ty1 ty2) = pprFunArgType ty1 <+> char '~' <+> pprFunArgType ty2
instance Ppr Range where
ppr = brackets . pprRange
where pprRange :: Range -> Doc
pprRange (FromR e) = ppr e <> text ".."
pprRange (FromThenR e1 e2) = ppr e1 <> text ","
<> ppr e2 <> text ".."
pprRange (FromToR e1 e2) = ppr e1 <> text ".." <> ppr e2
pprRange (FromThenToR e1 e2 e3) = ppr e1 <> text ","
<> ppr e2 <> text ".."
<> ppr e3
where_clause :: [Dec] -> Doc
where_clause [] = empty
where_clause ds = nest nestDepth $ text "where" <+> vcat (map (ppr_dec False) ds)
showtextl :: Show a => a -> Doc
showtextl = text . map toLower . show