module Language.Haskell.TH.Ppr where
import Text.PrettyPrint (render)
import Language.Haskell.TH.PprLib
import Language.Haskell.TH.Syntax
import Data.Word ( Word8 )
import Data.Char ( toLower, chr, ord, isSymbol )
import GHC.Show ( showMultiLineString )
import Data.Ratio ( numerator, denominator )
nestDepth :: Int
nestDepth = 4
type Precedence = Int
appPrec, unopPrec, opPrec, noPrec :: Precedence
appPrec = 3
opPrec = 2
unopPrec = 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 (TyConI d) = ppr d
ppr (ClassI d is) = ppr d $$ vcat (map ppr is)
ppr (FamilyI d is) = ppr d $$ vcat (map ppr is)
ppr (PrimTyConI name arity is_unlifted)
= text "Primitive"
<+> (if is_unlifted then text "unlifted" else empty)
<+> text "type constructor" <+> 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 }]
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 Module where
ppr (Module pkg m) = text (pkgString pkg) <+> text (modString m)
instance Ppr ModuleInfo where
ppr (ModuleInfo imps) = text "Module" <+> vcat (map ppr imps)
instance Ppr Exp where
ppr = pprExp noPrec
pprPrefixOcc :: Name -> Doc
pprPrefixOcc n = parensIf (isSymOcc n) (ppr n)
isSymOcc :: Name -> Bool
isSymOcc n
= case nameBase n of
[] -> True
(c:_) -> isSymbolASCII c || (ord c > 0x7f && isSymbol c)
isSymbolASCII :: Char -> Bool
isSymbolASCII c = c `elem` "!#$%&*+./<=>?@\\^|~-"
pprInfixExp :: Exp -> Doc
pprInfixExp (VarE v) = pprName' Infix v
pprInfixExp (ConE v) = pprName' Infix v
pprInfixExp _ = text "<<Non-variable/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 _ (ParensE e) = parens (pprExp noPrec e)
pprExp i (UInfixE e1 op e2)
= parensIf (i > unopPrec) $ pprExp unopPrec e1
<+> pprInfixExp op
<+> pprExp unopPrec 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 i (LamCaseE ms) = parensIf (i > noPrec)
$ text "\\case" $$ nest nestDepth (ppr ms)
pprExp _ (TupE es) = parens $ sep $ punctuate comma $ map ppr es
pprExp _ (UnboxedTupE es) = hashParens $ sep $ punctuate comma $ map ppr es
pprExp i (CondE guard true false)
= parensIf (i > noPrec) $ sep [text "if" <+> ppr guard,
nest 1 $ text "then" <+> ppr true,
nest 1 $ text "else" <+> ppr false]
pprExp i (MultiIfE alts)
= parensIf (i > noPrec) $ vcat $
case alts of
[] -> [text "if {}"]
(alt : alts') -> text "if" <+> pprGuarded arrow alt
: map (nest 3 . pprGuarded arrow) alts'
pprExp i (LetE ds_ e) = parensIf (i > noPrec) $ text "let" <+> pprDecs ds_
$$ text " in" <+> ppr e
where
pprDecs [] = empty
pprDecs [d] = ppr d
pprDecs ds = braces $ sep $ punctuate semi $ map ppr ds
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" <+> pprStms ss_
where
pprStms [] = empty
pprStms [s] = ppr s
pprStms ss = braces $ sep $ punctuate semi $ map ppr ss
pprExp _ (CompE []) = text "<<Empty 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
$$ where_clause ds
pprGuarded :: Doc -> (Guard, Exp) -> Doc
pprGuarded eqDoc (guard, expr) = case guard of
NormalG guardExpr -> char '|' <+> ppr guardExpr <+> eqDoc <+> ppr expr
PatG stmts -> char '|' <+> vcat (punctuate comma $ map ppr stmts) $$
nest nestDepth (eqDoc <+> ppr expr)
pprBody :: Bool -> Body -> Doc
pprBody eq body = case body of
GuardedB xs -> nest nestDepth $ vcat $ map (pprGuarded eqDoc) xs
NormalB e -> eqDoc <+> ppr e
where eqDoc | eq = equals
| otherwise = arrow
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) = pprString s
pprLit _ (StringPrimL s) = pprString (bytesToString s) <> char '#'
pprLit i (RationalL rat) = parensIf (i > noPrec) $
integer (numerator rat) <+> char '/'
<+> integer (denominator rat)
bytesToString :: [Word8] -> String
bytesToString = map (chr . fromIntegral)
pprString :: String -> Doc
pprString s = vcat (map text (showMultiLineString s))
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 _ (UnboxedTupP ps) = hashParens $ sep $ punctuate comma $ map ppr ps
pprPat i (ConP s ps) = parensIf (i >= appPrec) $ pprName' Applied s
<+> sep (map (pprPat appPrec) ps)
pprPat _ (ParensP p) = parens $ pprPat noPrec p
pprPat i (UInfixP p1 n p2)
= parensIf (i > unopPrec) (pprPat unopPrec p1 <+>
pprName' Infix n <+>
pprPat unopPrec p2)
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 -> pprPrefixOcc 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) = pprPrefixOcc f <+> text "::" <+> ppr t
ppr_dec _ (ForeignD f) = ppr f
ppr_dec _ (InfixD fx n) = pprFixity n fx
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 (TySynEqn tys rhs))
= ppr_tySyn maybeInst tc (sep (map pprParendType tys)) rhs
where
maybeInst | isTop = text "instance"
| otherwise = empty
ppr_dec _ (ClosedTypeFamilyD tc tvs mkind eqns)
= hang (hsep [ text "type family", ppr tc, hsep (map ppr tvs), maybeKind
, text "where" ])
nestDepth (vcat (map ppr_eqn eqns))
where
maybeKind | (Just k') <- mkind = text "::" <+> ppr k'
| otherwise = empty
ppr_eqn (TySynEqn lhs rhs)
= ppr tc <+> sep (map pprParendType lhs) <+> text "=" <+> ppr rhs
ppr_dec _ (RoleAnnotD name roles)
= hsep [ text "type role", ppr name ] <+> hsep (map ppr roles)
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 inline rm phases)
= text "{-#"
<+> ppr inline
<+> ppr rm
<+> ppr phases
<+> ppr n
<+> text "#-}"
ppr (SpecialiseP n ty inline phases)
= text "{-# SPECIALISE"
<+> maybe empty ppr inline
<+> ppr phases
<+> sep [ ppr n <+> text "::"
, nest 2 $ ppr ty ]
<+> text "#-}"
ppr (SpecialiseInstP inst)
= text "{-# SPECIALISE instance" <+> ppr inst <+> text "#-}"
ppr (RuleP n bndrs lhs rhs phases)
= sep [ text "{-# RULES" <+> pprString n <+> ppr phases
, nest 4 $ ppr_forall <+> ppr lhs
, nest 4 $ char '=' <+> ppr rhs <+> text "#-}" ]
where ppr_forall | null bndrs = empty
| otherwise = text "forall"
<+> fsep (map ppr bndrs)
<+> char '.'
ppr (AnnP tgt expr)
= text "{-# ANN" <+> target1 tgt <+> ppr expr <+> text "#-}"
where target1 ModuleAnnotation = text "module"
target1 (TypeAnnotation t) = text "type" <+> ppr t
target1 (ValueAnnotation v) = ppr v
instance Ppr Inline where
ppr NoInline = text "NOINLINE"
ppr Inline = text "INLINE"
ppr Inlinable = text "INLINABLE"
instance Ppr RuleMatch where
ppr ConLike = text "CONLIKE"
ppr FunLike = empty
instance Ppr Phases where
ppr AllPhases = empty
ppr (FromPhase i) = brackets $ int i
ppr (BeforePhase i) = brackets $ char '~' <> int i
instance Ppr RuleBndr where
ppr (RuleVar n) = ppr n
ppr (TypedRuleVar n ty) = parens $ ppr n <+> text "::" <+> ppr ty
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
pprStrictType (Unpacked, t) = text "{-# UNPACK #-} !" <> 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 (n-1) comma))
pprParendType (UnboxedTupleT n) = hashParens $ hcat $ replicate (n-1) comma
pprParendType ArrowT = parens (text "->")
pprParendType ListT = text "[]"
pprParendType (LitT l) = pprTyLit l
pprParendType (PromotedT c) = text "'" <> ppr c
pprParendType (PromotedTupleT 0) = text "'()"
pprParendType (PromotedTupleT n) = quoteParens (hcat (replicate (n-1) comma))
pprParendType PromotedNilT = text "'[]"
pprParendType PromotedConsT = text "(':)"
pprParendType StarT = char '*'
pprParendType ConstraintT = text "Constraint"
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 (PromotedTupleT n, args)
| length args == n = quoteParens (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)
pprTyLit :: TyLit -> Doc
pprTyLit (NumTyLit n) = integer n
pprTyLit (StrTyLit s) = text (show s)
instance Ppr TyLit where
ppr = pprTyLit
instance Ppr TyVarBndr where
ppr (PlainTV nm) = ppr nm
ppr (KindedTV nm k) = parens (ppr nm <+> text "::" <+> ppr k)
instance Ppr Role where
ppr NominalR = text "nominal"
ppr RepresentationalR = text "representational"
ppr PhantomR = text "phantom"
ppr InferR = text "_"
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
hashParens :: Doc -> Doc
hashParens d = text "(# " <> d <> text " #)"
quoteParens :: Doc -> Doc
quoteParens d = text "'(" <> d <> text ")"