Outputable.hs

{-
(c) The University of Glasgow 2006-2012
(c) The GRASP Project, Glasgow University, 1992-1998
-}

-- | This module defines classes and functions for pretty-printing. It also
-- exports a number of helpful debugging and other utilities such as 'trace' and 'panic'.
--
-- The interface to this module is very similar to the standard Hughes-PJ pretty printing
-- module, except that it exports a number of additional functions that are rarely used,
-- and works over the 'SDoc' type.
module Outputable (
        -- * Type classes
        Outputable(..), OutputableBndr(..),

        -- * Pretty printing combinators
        SDoc, runSDoc, initSDocContext,
        docToSDoc,
        interppSP, interpp'SP,
        pprQuotedList, pprWithCommas, quotedListWithOr, quotedListWithNor,
        pprWithBars,
        empty, isEmpty, nest,
        char,
        text, ftext, ptext, ztext,
        int, intWithCommas, integer, word, float, double, rational, doublePrec,
        parens, cparen, brackets, braces, quotes, quote,
        doubleQuotes, angleBrackets,
        semi, comma, colon, dcolon, space, equals, dot, vbar,
        arrow, larrow, darrow, arrowt, larrowt, arrowtt, larrowtt,
        lparen, rparen, lbrack, rbrack, lbrace, rbrace, underscore,
        blankLine, forAllLit, kindType, bullet,
        (<>), (<+>), hcat, hsep,
        ($$), ($+$), vcat,
        sep, cat,
        fsep, fcat,
        hang, hangNotEmpty, punctuate, ppWhen, ppUnless,
        speakNth, speakN, speakNOf, plural, isOrAre, doOrDoes,
        unicodeSyntax,

        coloured, keyword,

        -- * Converting 'SDoc' into strings and outputing it
        printSDoc, printSDocLn, printForUser, printForUserPartWay,
        printForC, bufLeftRenderSDoc,
        pprCode, mkCodeStyle,
        showSDoc, showSDocUnsafe, showSDocOneLine,
        showSDocForUser, showSDocDebug, showSDocDump, showSDocDumpOneLine,
        showSDocUnqual, showPpr,
        renderWithStyle,

        pprInfixVar, pprPrefixVar,
        pprHsChar, pprHsString, pprHsBytes,

        primFloatSuffix, primCharSuffix, primWordSuffix, primDoubleSuffix,
        primInt64Suffix, primWord64Suffix, primIntSuffix,

        pprPrimChar, pprPrimInt, pprPrimWord, pprPrimInt64, pprPrimWord64,

        pprFastFilePath, pprFilePathString,

        -- * Controlling the style in which output is printed
        BindingSite(..),

        PprStyle, CodeStyle(..), PrintUnqualified(..),
        QueryQualifyName, QueryQualifyModule, QueryQualifyPackage,
        reallyAlwaysQualify, reallyAlwaysQualifyNames,
        alwaysQualify, alwaysQualifyNames, alwaysQualifyModules,
        neverQualify, neverQualifyNames, neverQualifyModules,
        alwaysQualifyPackages, neverQualifyPackages,
        QualifyName(..), queryQual,
        sdocWithDynFlags, sdocWithPlatform,
        updSDocDynFlags,
        getPprStyle, withPprStyle, withPprStyleDoc, setStyleColoured,
        pprDeeper, pprDeeperList, pprSetDepth,
        codeStyle, userStyle, debugStyle, dumpStyle, asmStyle,
        qualName, qualModule, qualPackage,
        mkErrStyle, defaultErrStyle, defaultDumpStyle, mkDumpStyle, defaultUserStyle,
        mkUserStyle, cmdlineParserStyle, Depth(..),

        ifPprDebug, whenPprDebug, getPprDebug,

        -- * Error handling and debugging utilities
        pprPanic, pprSorry, assertPprPanic, pprPgmError,
        pprTrace, pprTraceDebug, pprTraceIt, warnPprTrace, pprSTrace,
        pprTraceException, pprTraceM,
        trace, pgmError, panic, sorry, assertPanic,
        pprDebugAndThen, callStackDoc,
    ) where

import GhcPrelude

import {-# SOURCE #-}   DynFlags( DynFlags, hasPprDebug, hasNoDebugOutput,
                                  targetPlatform, pprUserLength, pprCols,
                                  useUnicode, useUnicodeSyntax, useStarIsType,
                                  shouldUseColor, unsafeGlobalDynFlags,
                                  shouldUseHexWordLiterals )
import {-# SOURCE #-}   Module( UnitId, Module, ModuleName, moduleName )
import {-# SOURCE #-}   OccName( OccName )

import BufWrite (BufHandle)
import FastString
import qualified Pretty
import Util
import Platform
import qualified PprColour as Col
import Pretty           ( Doc, Mode(..) )
import Panic
import GHC.Serialized
import GHC.LanguageExtensions (Extension)

import Data.ByteString (ByteString)
import qualified Data.ByteString as BS
import Data.Char
import qualified Data.Map as M
import Data.Int
import qualified Data.IntMap as IM
import Data.Set (Set)
import qualified Data.Set as Set
import Data.String
import Data.Word
import System.IO        ( Handle )
import System.FilePath
import Text.Printf
import Numeric (showFFloat)
import Data.Graph (SCC(..))
import Data.List (intersperse)

import GHC.Fingerprint
import GHC.Show         ( showMultiLineString )
import GHC.Stack        ( callStack, prettyCallStack )
import Control.Monad.IO.Class
import Exception

{-
************************************************************************
*                                                                      *
\subsection{The @PprStyle@ data type}
*                                                                      *
************************************************************************
-}

data PprStyle
  = PprUser PrintUnqualified Depth Coloured
                -- Pretty-print in a way that will make sense to the
                -- ordinary user; must be very close to Haskell
                -- syntax, etc.
                -- Assumes printing tidied code: non-system names are
                -- printed without uniques.

  | PprDump PrintUnqualified
                -- For -ddump-foo; less verbose than PprDebug, but more than PprUser
                -- Does not assume tidied code: non-external names
                -- are printed with uniques.

  | PprDebug    -- Full debugging output

  | PprCode CodeStyle
                -- Print code; either C or assembler

data CodeStyle = CStyle         -- The format of labels differs for C and assembler
               | AsmStyle

data Depth = AllTheWay
           | PartWay Int        -- 0 => stop

data Coloured
  = Uncoloured
  | Coloured

-- -----------------------------------------------------------------------------
-- Printing original names

-- | When printing code that contains original names, we need to map the
-- original names back to something the user understands.  This is the
-- purpose of the triple of functions that gets passed around
-- when rendering 'SDoc'.
data PrintUnqualified = QueryQualify {
    queryQualifyName    :: QueryQualifyName,
    queryQualifyModule  :: QueryQualifyModule,
    queryQualifyPackage :: QueryQualifyPackage
}

-- | Given a `Name`'s `Module` and `OccName`, decide whether and how to qualify
-- it.
type QueryQualifyName = Module -> OccName -> QualifyName

-- | For a given module, we need to know whether to print it with
-- a package name to disambiguate it.
type QueryQualifyModule = Module -> Bool

-- | For a given package, we need to know whether to print it with
-- the component id to disambiguate it.
type QueryQualifyPackage = UnitId -> Bool

-- See Note [Printing original names] in HscTypes
data QualifyName   -- Given P:M.T
  = NameUnqual           -- It's in scope unqualified as "T"
                         -- OR nothing called "T" is in scope

  | NameQual ModuleName  -- It's in scope qualified as "X.T"

  | NameNotInScope1      -- It's not in scope at all, but M.T is not bound
                         -- in the current scope, so we can refer to it as "M.T"

  | NameNotInScope2      -- It's not in scope at all, and M.T is already bound in
                         -- the current scope, so we must refer to it as "P:M.T"

instance Outputable QualifyName where
  ppr NameUnqual      = text "NameUnqual"
  ppr (NameQual _mod) = text "NameQual"  -- can't print the mod without module loops :(
  ppr NameNotInScope1 = text "NameNotInScope1"
  ppr NameNotInScope2 = text "NameNotInScope2"

reallyAlwaysQualifyNames :: QueryQualifyName
reallyAlwaysQualifyNames _ _ = NameNotInScope2

-- | NB: This won't ever show package IDs
alwaysQualifyNames :: QueryQualifyName
alwaysQualifyNames m _ = NameQual (moduleName m)

neverQualifyNames :: QueryQualifyName
neverQualifyNames _ _ = NameUnqual

alwaysQualifyModules :: QueryQualifyModule
alwaysQualifyModules _ = True

neverQualifyModules :: QueryQualifyModule
neverQualifyModules _ = False

alwaysQualifyPackages :: QueryQualifyPackage
alwaysQualifyPackages _ = True

neverQualifyPackages :: QueryQualifyPackage
neverQualifyPackages _ = False

reallyAlwaysQualify, alwaysQualify, neverQualify :: PrintUnqualified
reallyAlwaysQualify
              = QueryQualify reallyAlwaysQualifyNames
                             alwaysQualifyModules
                             alwaysQualifyPackages
alwaysQualify = QueryQualify alwaysQualifyNames
                             alwaysQualifyModules
                             alwaysQualifyPackages
neverQualify  = QueryQualify neverQualifyNames
                             neverQualifyModules
                             neverQualifyPackages

defaultUserStyle :: DynFlags -> PprStyle
defaultUserStyle dflags = mkUserStyle dflags neverQualify AllTheWay

defaultDumpStyle :: DynFlags -> PprStyle
 -- Print without qualifiers to reduce verbosity, unless -dppr-debug
defaultDumpStyle dflags
   | hasPprDebug dflags = PprDebug
   | otherwise          = PprDump neverQualify

mkDumpStyle :: DynFlags -> PrintUnqualified -> PprStyle
mkDumpStyle dflags print_unqual
   | hasPprDebug dflags = PprDebug
   | otherwise          = PprDump print_unqual

defaultErrStyle :: DynFlags -> PprStyle
-- Default style for error messages, when we don't know PrintUnqualified
-- It's a bit of a hack because it doesn't take into account what's in scope
-- Only used for desugarer warnings, and typechecker errors in interface sigs
-- NB that -dppr-debug will still get into PprDebug style
defaultErrStyle dflags = mkErrStyle dflags neverQualify

-- | Style for printing error messages
mkErrStyle :: DynFlags -> PrintUnqualified -> PprStyle
mkErrStyle dflags qual =
   mkUserStyle dflags qual (PartWay (pprUserLength dflags))

cmdlineParserStyle :: DynFlags -> PprStyle
cmdlineParserStyle dflags = mkUserStyle dflags alwaysQualify AllTheWay

mkUserStyle :: DynFlags -> PrintUnqualified -> Depth -> PprStyle
mkUserStyle dflags unqual depth
   | hasPprDebug dflags = PprDebug
   | otherwise          = PprUser unqual depth Uncoloured

setStyleColoured :: Bool -> PprStyle -> PprStyle
setStyleColoured col style =
  case style of
    PprUser q d _ -> PprUser q d c
    _             -> style
  where
    c | col       = Coloured
      | otherwise = Uncoloured

instance Outputable PprStyle where
  ppr (PprUser {})  = text "user-style"
  ppr (PprCode {})  = text "code-style"
  ppr (PprDump {})  = text "dump-style"
  ppr (PprDebug {}) = text "debug-style"

{-
Orthogonal to the above printing styles are (possibly) some
command-line flags that affect printing (often carried with the
style).  The most likely ones are variations on how much type info is
shown.

The following test decides whether or not we are actually generating
code (either C or assembly), or generating interface files.

************************************************************************
*                                                                      *
\subsection{The @SDoc@ data type}
*                                                                      *
************************************************************************
-}

-- | Represents a pretty-printable document.
--
-- To display an 'SDoc', use 'printSDoc', 'printSDocLn', 'bufLeftRenderSDoc',
-- or 'renderWithStyle'.  Avoid calling 'runSDoc' directly as it breaks the
-- abstraction layer.
newtype SDoc = SDoc { runSDoc :: SDocContext -> Doc }

data SDocContext = SDC
  { sdocStyle      :: !PprStyle
  , sdocLastColour :: !Col.PprColour
    -- ^ The most recently used colour.  This allows nesting colours.
  , sdocDynFlags   :: !DynFlags
  }

instance IsString SDoc where
  fromString = text

initSDocContext :: DynFlags -> PprStyle -> SDocContext
initSDocContext dflags sty = SDC
  { sdocStyle = sty
  , sdocLastColour = Col.colReset
  , sdocDynFlags = dflags
  }

withPprStyle :: PprStyle -> SDoc -> SDoc
withPprStyle sty d = SDoc $ \ctxt -> runSDoc d ctxt{sdocStyle=sty}

-- | This is not a recommended way to render 'SDoc', since it breaks the
-- abstraction layer of 'SDoc'.  Prefer to use 'printSDoc', 'printSDocLn',
-- 'bufLeftRenderSDoc', or 'renderWithStyle' instead.
withPprStyleDoc :: DynFlags -> PprStyle -> SDoc -> Doc
withPprStyleDoc dflags sty d = runSDoc d (initSDocContext dflags sty)

pprDeeper :: SDoc -> SDoc
pprDeeper d = SDoc $ \ctx -> case ctx of
  SDC{sdocStyle=PprUser _ (PartWay 0) _} -> Pretty.text "..."
  SDC{sdocStyle=PprUser q (PartWay n) c} ->
    runSDoc d ctx{sdocStyle = PprUser q (PartWay (n-1)) c}
  _ -> runSDoc d ctx

-- | Truncate a list that is longer than the current depth.
pprDeeperList :: ([SDoc] -> SDoc) -> [SDoc] -> SDoc
pprDeeperList f ds
  | null ds   = f []
  | otherwise = SDoc work
 where
  work ctx@SDC{sdocStyle=PprUser q (PartWay n) c}
   | n==0      = Pretty.text "..."
   | otherwise =
      runSDoc (f (go 0 ds)) ctx{sdocStyle = PprUser q (PartWay (n-1)) c}
   where
     go _ [] = []
     go i (d:ds) | i >= n    = [text "...."]
                 | otherwise = d : go (i+1) ds
  work other_ctx = runSDoc (f ds) other_ctx

pprSetDepth :: Depth -> SDoc -> SDoc
pprSetDepth depth doc = SDoc $ \ctx ->
    case ctx of
        SDC{sdocStyle=PprUser q _ c} ->
            runSDoc doc ctx{sdocStyle = PprUser q depth c}
        _ ->
            runSDoc doc ctx

getPprStyle :: (PprStyle -> SDoc) -> SDoc
getPprStyle df = SDoc $ \ctx -> runSDoc (df (sdocStyle ctx)) ctx

sdocWithDynFlags :: (DynFlags -> SDoc) -> SDoc
sdocWithDynFlags f = SDoc $ \ctx -> runSDoc (f (sdocDynFlags ctx)) ctx

sdocWithPlatform :: (Platform -> SDoc) -> SDoc
sdocWithPlatform f = sdocWithDynFlags (f . targetPlatform)

updSDocDynFlags :: (DynFlags -> DynFlags) -> SDoc -> SDoc
updSDocDynFlags upd doc
  = SDoc $ \ctx -> runSDoc doc (ctx { sdocDynFlags = upd (sdocDynFlags ctx) })

qualName :: PprStyle -> QueryQualifyName
qualName (PprUser q _ _) mod occ = queryQualifyName q mod occ
qualName (PprDump q)     mod occ = queryQualifyName q mod occ
qualName _other          mod _   = NameQual (moduleName mod)

qualModule :: PprStyle -> QueryQualifyModule
qualModule (PprUser q _ _)  m = queryQualifyModule q m
qualModule (PprDump q)      m = queryQualifyModule q m
qualModule _other          _m = True

qualPackage :: PprStyle -> QueryQualifyPackage
qualPackage (PprUser q _ _)  m = queryQualifyPackage q m
qualPackage (PprDump q)      m = queryQualifyPackage q m
qualPackage _other          _m = True

queryQual :: PprStyle -> PrintUnqualified
queryQual s = QueryQualify (qualName s)
                           (qualModule s)
                           (qualPackage s)

codeStyle :: PprStyle -> Bool
codeStyle (PprCode _)     = True
codeStyle _               = False

asmStyle :: PprStyle -> Bool
asmStyle (PprCode AsmStyle)  = True
asmStyle _other              = False

dumpStyle :: PprStyle -> Bool
dumpStyle (PprDump {}) = True
dumpStyle _other       = False

debugStyle :: PprStyle -> Bool
debugStyle PprDebug = True
debugStyle _other   = False

userStyle ::  PprStyle -> Bool
userStyle (PprUser {}) = True
userStyle _other       = False

getPprDebug :: (Bool -> SDoc) -> SDoc
getPprDebug d = getPprStyle $ \ sty -> d (debugStyle sty)

ifPprDebug :: SDoc -> SDoc -> SDoc
-- ^ Says what to do with and without -dppr-debug
ifPprDebug yes no = getPprDebug $ \ dbg -> if dbg then yes else no

whenPprDebug :: SDoc -> SDoc        -- Empty for non-debug style
-- ^ Says what to do with -dppr-debug; without, return empty
whenPprDebug d = ifPprDebug d empty

-- | The analog of 'Pretty.printDoc_' for 'SDoc', which tries to make sure the
--   terminal doesn't get screwed up by the ANSI color codes if an exception
--   is thrown during pretty-printing.
printSDoc :: Mode -> DynFlags -> Handle -> PprStyle -> SDoc -> IO ()
printSDoc mode dflags handle sty doc =
  Pretty.printDoc_ mode cols handle (runSDoc doc ctx)
    `finally`
      Pretty.printDoc_ mode cols handle
        (runSDoc (coloured Col.colReset empty) ctx)
  where
    cols = pprCols dflags
    ctx = initSDocContext dflags sty

-- | Like 'printSDoc' but appends an extra newline.
printSDocLn :: Mode -> DynFlags -> Handle -> PprStyle -> SDoc -> IO ()
printSDocLn mode dflags handle sty doc =
  printSDoc mode dflags handle sty (doc $$ text "")

printForUser :: DynFlags -> Handle -> PrintUnqualified -> SDoc -> IO ()
printForUser dflags handle unqual doc
  = printSDocLn PageMode dflags handle
               (mkUserStyle dflags unqual AllTheWay) doc

printForUserPartWay :: DynFlags -> Handle -> Int -> PrintUnqualified -> SDoc
                    -> IO ()
printForUserPartWay dflags handle d unqual doc
  = printSDocLn PageMode dflags handle
                (mkUserStyle dflags unqual (PartWay d)) doc

-- | Like 'printSDocLn' but specialized with 'LeftMode' and
-- @'PprCode' 'CStyle'@.  This is typically used to output C-- code.
printForC :: DynFlags -> Handle -> SDoc -> IO ()
printForC dflags handle doc =
  printSDocLn LeftMode dflags handle (PprCode CStyle) doc

-- | An efficient variant of 'printSDoc' specialized for 'LeftMode' that
-- outputs to a 'BufHandle'.
bufLeftRenderSDoc :: DynFlags -> BufHandle -> PprStyle -> SDoc -> IO ()
bufLeftRenderSDoc dflags bufHandle sty doc =
  Pretty.bufLeftRender bufHandle (runSDoc doc (initSDocContext dflags sty))

pprCode :: CodeStyle -> SDoc -> SDoc
pprCode cs d = withPprStyle (PprCode cs) d

mkCodeStyle :: CodeStyle -> PprStyle
mkCodeStyle = PprCode

-- Can't make SDoc an instance of Show because SDoc is just a function type
-- However, Doc *is* an instance of Show
-- showSDoc just blasts it out as a string
showSDoc :: DynFlags -> SDoc -> String
showSDoc dflags sdoc = renderWithStyle dflags sdoc (defaultUserStyle dflags)

-- showSDocUnsafe is unsafe, because `unsafeGlobalDynFlags` might not be
-- initialised yet.
showSDocUnsafe :: SDoc -> String
showSDocUnsafe sdoc = showSDoc unsafeGlobalDynFlags sdoc

showPpr :: Outputable a => DynFlags -> a -> String
showPpr dflags thing = showSDoc dflags (ppr thing)

showSDocUnqual :: DynFlags -> SDoc -> String
-- Only used by Haddock
showSDocUnqual dflags sdoc = showSDoc dflags sdoc

showSDocForUser :: DynFlags -> PrintUnqualified -> SDoc -> String
-- Allows caller to specify the PrintUnqualified to use
showSDocForUser dflags unqual doc
 = renderWithStyle dflags doc (mkUserStyle dflags unqual AllTheWay)

showSDocDump :: DynFlags -> SDoc -> String
showSDocDump dflags d = renderWithStyle dflags d (defaultDumpStyle dflags)

showSDocDebug :: DynFlags -> SDoc -> String
showSDocDebug dflags d = renderWithStyle dflags d PprDebug

renderWithStyle :: DynFlags -> SDoc -> PprStyle -> String
renderWithStyle dflags sdoc sty
  = let s = Pretty.style{ Pretty.mode = PageMode,
                          Pretty.lineLength = pprCols dflags }
    in Pretty.renderStyle s $ runSDoc sdoc (initSDocContext dflags sty)

-- This shows an SDoc, but on one line only. It's cheaper than a full
-- showSDoc, designed for when we're getting results like "Foo.bar"
-- and "foo{uniq strictness}" so we don't want fancy layout anyway.
showSDocOneLine :: DynFlags -> SDoc -> String
showSDocOneLine dflags d
 = let s = Pretty.style{ Pretty.mode = OneLineMode,
                         Pretty.lineLength = pprCols dflags } in
   Pretty.renderStyle s $
      runSDoc d (initSDocContext dflags (defaultUserStyle dflags))

showSDocDumpOneLine :: DynFlags -> SDoc -> String
showSDocDumpOneLine dflags d
 = let s = Pretty.style{ Pretty.mode = OneLineMode,
                         Pretty.lineLength = irrelevantNCols } in
   Pretty.renderStyle s $
      runSDoc d (initSDocContext dflags (defaultDumpStyle dflags))

irrelevantNCols :: Int
-- Used for OneLineMode and LeftMode when number of cols isn't used
irrelevantNCols = 1

isEmpty :: DynFlags -> SDoc -> Bool
isEmpty dflags sdoc = Pretty.isEmpty $ runSDoc sdoc dummySDocContext
   where dummySDocContext = initSDocContext dflags PprDebug

docToSDoc :: Doc -> SDoc
docToSDoc d = SDoc (\_ -> d)

empty    :: SDoc
char     :: Char       -> SDoc
text     :: String     -> SDoc
ftext    :: FastString -> SDoc
ptext    :: PtrString  -> SDoc
ztext    :: FastZString -> SDoc
int      :: Int        -> SDoc
integer  :: Integer    -> SDoc
word     :: Integer    -> SDoc
float    :: Float      -> SDoc
double   :: Double     -> SDoc
rational :: Rational   -> SDoc

empty       = docToSDoc $ Pretty.empty
char c      = docToSDoc $ Pretty.char c

text s      = docToSDoc $ Pretty.text s
{-# INLINE text #-}   -- Inline so that the RULE Pretty.text will fire

ftext s     = docToSDoc $ Pretty.ftext s
ptext s     = docToSDoc $ Pretty.ptext s
ztext s     = docToSDoc $ Pretty.ztext s
int n       = docToSDoc $ Pretty.int n
integer n   = docToSDoc $ Pretty.integer n
float n     = docToSDoc $ Pretty.float n
double n    = docToSDoc $ Pretty.double n
rational n  = docToSDoc $ Pretty.rational n
word n      = sdocWithDynFlags $ \dflags ->
    -- See Note [Print Hexadecimal Literals] in Pretty.hs
    if shouldUseHexWordLiterals dflags
        then docToSDoc $ Pretty.hex n
        else docToSDoc $ Pretty.integer n

-- | @doublePrec p n@ shows a floating point number @n@ with @p@
-- digits of precision after the decimal point.
doublePrec :: Int -> Double -> SDoc
doublePrec p n = text (showFFloat (Just p) n "")

parens, braces, brackets, quotes, quote,
        doubleQuotes, angleBrackets :: SDoc -> SDoc

parens d        = SDoc $ Pretty.parens . runSDoc d
braces d        = SDoc $ Pretty.braces . runSDoc d
brackets d      = SDoc $ Pretty.brackets . runSDoc d
quote d         = SDoc $ Pretty.quote . runSDoc d
doubleQuotes d  = SDoc $ Pretty.doubleQuotes . runSDoc d
angleBrackets d = char '<' <> d <> char '>'

cparen :: Bool -> SDoc -> SDoc
cparen b d = SDoc $ Pretty.maybeParens b . runSDoc d

-- 'quotes' encloses something in single quotes...
-- but it omits them if the thing begins or ends in a single quote
-- so that we don't get `foo''.  Instead we just have foo'.
quotes d =
      sdocWithDynFlags $ \dflags ->
      if useUnicode dflags
      then char '‘' <> d <> char '’'
      else SDoc $ \sty ->
           let pp_d = runSDoc d sty
               str  = show pp_d
           in case (str, lastMaybe str) of
             (_, Just '\'') -> pp_d
             ('\'' : _, _)       -> pp_d
             _other              -> Pretty.quotes pp_d

semi, comma, colon, equals, space, dcolon, underscore, dot, vbar :: SDoc
arrow, larrow, darrow, arrowt, larrowt, arrowtt, larrowtt :: SDoc
lparen, rparen, lbrack, rbrack, lbrace, rbrace, blankLine :: SDoc

blankLine  = docToSDoc $ Pretty.text ""
dcolon     = unicodeSyntax (char '∷') (docToSDoc $ Pretty.text "::")
arrow      = unicodeSyntax (char '→') (docToSDoc $ Pretty.text "->")
larrow     = unicodeSyntax (char '←') (docToSDoc $ Pretty.text "<-")
darrow     = unicodeSyntax (char '⇒') (docToSDoc $ Pretty.text "=>")
arrowt     = unicodeSyntax (char '⤚') (docToSDoc $ Pretty.text ">-")
larrowt    = unicodeSyntax (char '⤙') (docToSDoc $ Pretty.text "-<")
arrowtt    = unicodeSyntax (char '⤜') (docToSDoc $ Pretty.text ">>-")
larrowtt   = unicodeSyntax (char '⤛') (docToSDoc $ Pretty.text "-<<")
semi       = docToSDoc $ Pretty.semi
comma      = docToSDoc $ Pretty.comma
colon      = docToSDoc $ Pretty.colon
equals     = docToSDoc $ Pretty.equals
space      = docToSDoc $ Pretty.space
underscore = char '_'
dot        = char '.'
vbar       = char '|'
lparen     = docToSDoc $ Pretty.lparen
rparen     = docToSDoc $ Pretty.rparen
lbrack     = docToSDoc $ Pretty.lbrack
rbrack     = docToSDoc $ Pretty.rbrack
lbrace     = docToSDoc $ Pretty.lbrace
rbrace     = docToSDoc $ Pretty.rbrace

forAllLit :: SDoc
forAllLit = unicodeSyntax (char '∀') (text "forall")

kindType :: SDoc
kindType = sdocWithDynFlags $ \dflags ->
    if useStarIsType dflags
    then unicodeSyntax (char '★') (char '*')
    else text "Type"

bullet :: SDoc
bullet = unicode (char '•') (char '*')

unicodeSyntax :: SDoc -> SDoc -> SDoc
unicodeSyntax unicode plain = sdocWithDynFlags $ \dflags ->
    if useUnicode dflags && useUnicodeSyntax dflags
    then unicode
    else plain

unicode :: SDoc -> SDoc -> SDoc
unicode unicode plain = sdocWithDynFlags $ \dflags ->
    if useUnicode dflags
    then unicode
    else plain

nest :: Int -> SDoc -> SDoc
-- ^ Indent 'SDoc' some specified amount
(<>) :: SDoc -> SDoc -> SDoc
-- ^ Join two 'SDoc' together horizontally without a gap
(<+>) :: SDoc -> SDoc -> SDoc
-- ^ Join two 'SDoc' together horizontally with a gap between them
($$) :: SDoc -> SDoc -> SDoc
-- ^ Join two 'SDoc' together vertically; if there is
-- no vertical overlap it "dovetails" the two onto one line
($+$) :: SDoc -> SDoc -> SDoc
-- ^ Join two 'SDoc' together vertically

nest n d    = SDoc $ Pretty.nest n . runSDoc d
(<>) d1 d2  = SDoc $ \sty -> (Pretty.<>)  (runSDoc d1 sty) (runSDoc d2 sty)
(<+>) d1 d2 = SDoc $ \sty -> (Pretty.<+>) (runSDoc d1 sty) (runSDoc d2 sty)
($$) d1 d2  = SDoc $ \sty -> (Pretty.$$)  (runSDoc d1 sty) (runSDoc d2 sty)
($+$) d1 d2 = SDoc $ \sty -> (Pretty.$+$) (runSDoc d1 sty) (runSDoc d2 sty)

hcat :: [SDoc] -> SDoc
-- ^ Concatenate 'SDoc' horizontally
hsep :: [SDoc] -> SDoc
-- ^ Concatenate 'SDoc' horizontally with a space between each one
vcat :: [SDoc] -> SDoc
-- ^ Concatenate 'SDoc' vertically with dovetailing
sep :: [SDoc] -> SDoc
-- ^ Separate: is either like 'hsep' or like 'vcat', depending on what fits
cat :: [SDoc] -> SDoc
-- ^ Catenate: is either like 'hcat' or like 'vcat', depending on what fits
fsep :: [SDoc] -> SDoc
-- ^ A paragraph-fill combinator. It's much like sep, only it
-- keeps fitting things on one line until it can't fit any more.
fcat :: [SDoc] -> SDoc
-- ^ This behaves like 'fsep', but it uses '<>' for horizontal conposition rather than '<+>'


hcat ds = SDoc $ \sty -> Pretty.hcat [runSDoc d sty | d <- ds]
hsep ds = SDoc $ \sty -> Pretty.hsep [runSDoc d sty | d <- ds]
vcat ds = SDoc $ \sty -> Pretty.vcat [runSDoc d sty | d <- ds]
sep ds  = SDoc $ \sty -> Pretty.sep  [runSDoc d sty | d <- ds]
cat ds  = SDoc $ \sty -> Pretty.cat  [runSDoc d sty | d <- ds]
fsep ds = SDoc $ \sty -> Pretty.fsep [runSDoc d sty | d <- ds]
fcat ds = SDoc $ \sty -> Pretty.fcat [runSDoc d sty | d <- ds]

hang :: SDoc  -- ^ The header
      -> Int  -- ^ Amount to indent the hung body
      -> SDoc -- ^ The hung body, indented and placed below the header
      -> SDoc
hang d1 n d2   = SDoc $ \sty -> Pretty.hang (runSDoc d1 sty) n (runSDoc d2 sty)

-- | This behaves like 'hang', but does not indent the second document
-- when the header is empty.
hangNotEmpty :: SDoc -> Int -> SDoc -> SDoc
hangNotEmpty d1 n d2 =
    SDoc $ \sty -> Pretty.hangNotEmpty (runSDoc d1 sty) n (runSDoc d2 sty)

punctuate :: SDoc   -- ^ The punctuation
          -> [SDoc] -- ^ The list that will have punctuation added between every adjacent pair of elements
          -> [SDoc] -- ^ Punctuated list
punctuate _ []     = []
punctuate p (d:ds) = go d ds
                   where
                     go d [] = [d]
                     go d (e:es) = (d <> p) : go e es

ppWhen, ppUnless :: Bool -> SDoc -> SDoc
ppWhen True  doc = doc
ppWhen False _   = empty

ppUnless True  _   = empty
ppUnless False doc = doc

-- | Apply the given colour\/style for the argument.
--
-- Only takes effect if colours are enabled.
coloured :: Col.PprColour -> SDoc -> SDoc
coloured col sdoc =
  sdocWithDynFlags $ \dflags ->
    if shouldUseColor dflags
    then SDoc $ \ctx@SDC{ sdocLastColour = lastCol } ->
         case ctx of
           SDC{ sdocStyle = PprUser _ _ Coloured } ->
             let ctx' = ctx{ sdocLastColour = lastCol `mappend` col } in
             Pretty.zeroWidthText (Col.renderColour col)
               Pretty.<> runSDoc sdoc ctx'
               Pretty.<> Pretty.zeroWidthText (Col.renderColourAfresh lastCol)
           _ -> runSDoc sdoc ctx
    else sdoc

keyword :: SDoc -> SDoc
keyword = coloured Col.colBold

{-
************************************************************************
*                                                                      *
\subsection[Outputable-class]{The @Outputable@ class}
*                                                                      *
************************************************************************
-}

-- | Class designating that some type has an 'SDoc' representation
class Outputable a where
        ppr :: a -> SDoc
        pprPrec :: Rational -> a -> SDoc
                -- 0 binds least tightly
                -- We use Rational because there is always a
                -- Rational between any other two Rationals

        ppr = pprPrec 0
        pprPrec _ = ppr

instance Outputable Char where
    ppr c = text [c]

instance Outputable Bool where
    ppr True  = text "True"
    ppr False = text "False"

instance Outputable Ordering where
    ppr LT = text "LT"
    ppr EQ = text "EQ"
    ppr GT = text "GT"

instance Outputable Int32 where
   ppr n = integer $ fromIntegral n

instance Outputable Int64 where
   ppr n = integer $ fromIntegral n

instance Outputable Int where
    ppr n = int n

instance Outputable Integer where
    ppr n = integer n

instance Outputable Word16 where
    ppr n = integer $ fromIntegral n

instance Outputable Word32 where
    ppr n = integer $ fromIntegral n

instance Outputable Word where
    ppr n = integer $ fromIntegral n

instance Outputable () where
    ppr _ = text "()"

instance (Outputable a) => Outputable [a] where
    ppr xs = brackets (fsep (punctuate comma (map ppr xs)))

instance (Outputable a) => Outputable (Set a) where
    ppr s = braces (fsep (punctuate comma (map ppr (Set.toList s))))

instance (Outputable a, Outputable b) => Outputable (a, b) where
    ppr (x,y) = parens (sep [ppr x <> comma, ppr y])

instance Outputable a => Outputable (Maybe a) where