{-# LANGUAGE LambdaCase #-} {-# LANGUAGE PatternSynonyms #-} {-# LANGUAGE StandaloneDeriving #-} {-# LANGUAGE DerivingStrategies #-} {-# LANGUAGE GeneralizedNewtypeDeriving #-} {-# LANGUAGE FlexibleInstances #-} {-# LANGUAGE MultiParamTypeClasses #-} {- (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 GHC.Utils.Outputable ( -- * Type classes Outputable(..), OutputableBndr(..), OutputableP(..), -- * Pretty printing combinators SDoc, runSDoc, PDoc(..), docToSDoc, interppSP, interpp'SP, 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, lollipop, larrow, darrow, arrowt, larrowt, arrowtt, larrowtt, lambda, lparen, rparen, lbrack, rbrack, lbrace, rbrace, underscore, mulArrow, blankLine, forAllLit, bullet, (<>), (<+>), hcat, hsep, ($$), ($+$), vcat, sep, cat, fsep, fcat, hang, hangNotEmpty, punctuate, ppWhen, ppUnless, ppWhenOption, ppUnlessOption, speakNth, speakN, speakNOf, plural, isOrAre, doOrDoes, itsOrTheir, unicodeSyntax, coloured, keyword, -- * Converting 'SDoc' into strings and outputting it printSDoc, printSDocLn, bufLeftRenderSDoc, pprCode, showSDocUnsafe, showPprUnsafe, showSDocOneLine, renderWithContext, pprInfixVar, pprPrefixVar, pprHsChar, pprHsString, pprHsBytes, primFloatSuffix, primCharSuffix, primDoubleSuffix, primInt8Suffix, primWord8Suffix, primInt16Suffix, primWord16Suffix, primInt32Suffix, primWord32Suffix, primInt64Suffix, primWord64Suffix, primIntSuffix, primWordSuffix, pprPrimChar, pprPrimInt, pprPrimWord, pprPrimInt8, pprPrimWord8, pprPrimInt16, pprPrimWord16, pprPrimInt32, pprPrimWord32, pprPrimInt64, pprPrimWord64, pprFastFilePath, pprFilePathString, -- * Controlling the style in which output is printed BindingSite(..), PprStyle(..), LabelStyle(..), PrintUnqualified(..), QueryQualifyName, QueryQualifyModule, QueryQualifyPackage, reallyAlwaysQualify, reallyAlwaysQualifyNames, alwaysQualify, alwaysQualifyNames, alwaysQualifyModules, neverQualify, neverQualifyNames, neverQualifyModules, alwaysQualifyPackages, neverQualifyPackages, QualifyName(..), queryQual, sdocOption, updSDocContext, SDocContext (..), sdocWithContext, defaultSDocContext, getPprStyle, withPprStyle, setStyleColoured, pprDeeper, pprDeeperList, pprSetDepth, codeStyle, userStyle, dumpStyle, asmStyle, qualName, qualModule, qualPackage, mkErrStyle, defaultErrStyle, defaultDumpStyle, mkDumpStyle, defaultUserStyle, mkUserStyle, cmdlineParserStyle, Depth(..), withUserStyle, withErrStyle, ifPprDebug, whenPprDebug, getPprDebug, ) where import GHC.Prelude import {-# SOURCE #-} GHC.Unit.Types ( Unit, Module, moduleName ) import {-# SOURCE #-} GHC.Unit.Module.Name( ModuleName ) import {-# SOURCE #-} GHC.Types.Name.Occurrence( OccName ) import GHC.Utils.BufHandle (BufHandle) import GHC.Data.FastString import qualified GHC.Utils.Ppr as Pretty import qualified GHC.Utils.Ppr.Colour as Col import GHC.Utils.Ppr ( Doc, Mode(..) ) 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 qualified Data.IntSet as IntSet 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 Data.List.NonEmpty (NonEmpty (..)) import qualified Data.List.NonEmpty as NEL import GHC.Fingerprint import GHC.Show ( showMultiLineString ) import GHC.Utils.Exception import GHC.Exts (oneShot) {- ************************************************************************ * * \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 in ppr-debug mode, but more than PprUser -- Does not assume tidied code: non-external names -- are printed with uniques. | PprCode LabelStyle -- ^ Print code; either C or assembler -- | Style of label pretty-printing. -- -- When we produce C sources or headers, we have to take into account that C -- compilers transform C labels when they convert them into symbols. For -- example, they can add prefixes (e.g., "_" on Darwin) or suffixes (size for -- stdcalls on Windows). So we provide two ways to pretty-print CLabels: C style -- or Asm style. -- data LabelStyle = CStyle -- ^ C label style (used by C and LLVM backends) | AsmStyle -- ^ Asm label style (used by NCG backend) deriving (Eq,Ord,Show) data Depth = AllTheWay | PartWay Int -- ^ 0 => stop | DefaultDepth -- ^ Use 'sdocDefaultDepth' field as depth 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 = Unit -> Bool -- See Note [Printing original names] in GHC.Types.Name.Ppr 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 :: PprStyle defaultUserStyle = mkUserStyle neverQualify AllTheWay defaultDumpStyle :: PprStyle -- Print without qualifiers to reduce verbosity, unless -dppr-debug defaultDumpStyle = PprDump neverQualify mkDumpStyle :: PrintUnqualified -> PprStyle mkDumpStyle print_unqual = PprDump print_unqual -- | 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 defaultErrStyle :: PprStyle defaultErrStyle = mkErrStyle neverQualify -- | Style for printing error messages mkErrStyle :: PrintUnqualified -> PprStyle mkErrStyle unqual = mkUserStyle unqual DefaultDepth cmdlineParserStyle :: PprStyle cmdlineParserStyle = mkUserStyle alwaysQualify AllTheWay mkUserStyle :: PrintUnqualified -> Depth -> PprStyle mkUserStyle unqual depth = PprUser unqual depth Uncoloured withUserStyle :: PrintUnqualified -> Depth -> SDoc -> SDoc withUserStyle unqual depth doc = withPprStyle (PprUser unqual depth Uncoloured) doc withErrStyle :: PrintUnqualified -> SDoc -> SDoc withErrStyle unqual doc = withPprStyle (mkErrStyle unqual) doc 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" {- 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 'renderWithContext'. Avoid calling 'runSDoc' directly as it breaks the -- abstraction layer. newtype SDoc = SDoc' (SDocContext -> Doc) -- See Note [The one-shot state monad trick] in GHC.Utils.Monad {-# COMPLETE SDoc #-} pattern SDoc :: (SDocContext -> Doc) -> SDoc pattern SDoc m <- SDoc' m where SDoc m = SDoc' (oneShot m) runSDoc :: SDoc -> (SDocContext -> Doc) runSDoc (SDoc m) = m data SDocContext = SDC { sdocStyle :: !PprStyle , sdocColScheme :: !Col.Scheme , sdocLastColour :: !Col.PprColour -- ^ The most recently used colour. -- This allows nesting colours. , sdocShouldUseColor :: !Bool , sdocDefaultDepth :: !Int , sdocLineLength :: !Int , sdocCanUseUnicode :: !Bool -- ^ True if Unicode encoding is supported -- and not disable by GHC_NO_UNICODE environment variable , sdocHexWordLiterals :: !Bool , sdocPprDebug :: !Bool , sdocPrintUnicodeSyntax :: !Bool , sdocPrintCaseAsLet :: !Bool , sdocPrintTypecheckerElaboration :: !Bool , sdocPrintAxiomIncomps :: !Bool , sdocPrintExplicitKinds :: !Bool , sdocPrintExplicitCoercions :: !Bool , sdocPrintExplicitRuntimeReps :: !Bool , sdocPrintExplicitForalls :: !Bool , sdocPrintPotentialInstances :: !Bool , sdocPrintEqualityRelations :: !Bool , sdocSuppressTicks :: !Bool , sdocSuppressTypeSignatures :: !Bool , sdocSuppressTypeApplications :: !Bool , sdocSuppressIdInfo :: !Bool , sdocSuppressCoercions :: !Bool , sdocSuppressUnfoldings :: !Bool , sdocSuppressVarKinds :: !Bool , sdocSuppressUniques :: !Bool , sdocSuppressModulePrefixes :: !Bool , sdocSuppressStgExts :: !Bool , sdocErrorSpans :: !Bool , sdocStarIsType :: !Bool , sdocLinearTypes :: !Bool , sdocImpredicativeTypes :: !Bool , sdocPrintTypeAbbreviations :: !Bool , sdocUnitIdForUser :: !(FastString -> SDoc) -- ^ Used to map UnitIds to more friendly "package-version:component" -- strings while pretty-printing. -- -- Use `GHC.Unit.State.pprWithUnitState` to set it. Users should never -- have to set it to pretty-print SDocs emitted by GHC, otherwise it's a -- bug. It's an internal field used to thread the UnitState so that the -- Outputable instance of UnitId can use it. -- -- See Note [Pretty-printing UnitId] in "GHC.Unit" for more details. -- -- Note that we use `FastString` instead of `UnitId` to avoid boring -- module inter-dependency issues. } instance IsString SDoc where fromString = text -- The lazy programmer's friend. instance Outputable SDoc where ppr = id -- | Default pretty-printing options defaultSDocContext :: SDocContext defaultSDocContext = SDC { sdocStyle = defaultDumpStyle , sdocColScheme = Col.defaultScheme , sdocLastColour = Col.colReset , sdocShouldUseColor = False , sdocDefaultDepth = 5 , sdocLineLength = 100 , sdocCanUseUnicode = False , sdocHexWordLiterals = False , sdocPprDebug = False , sdocPrintUnicodeSyntax = False , sdocPrintCaseAsLet = False , sdocPrintTypecheckerElaboration = False , sdocPrintAxiomIncomps = False , sdocPrintExplicitKinds = False , sdocPrintExplicitCoercions = False , sdocPrintExplicitRuntimeReps = False , sdocPrintExplicitForalls = False , sdocPrintPotentialInstances = False , sdocPrintEqualityRelations = False , sdocSuppressTicks = False , sdocSuppressTypeSignatures = False , sdocSuppressTypeApplications = False , sdocSuppressIdInfo = False , sdocSuppressCoercions = False , sdocSuppressUnfoldings = False , sdocSuppressVarKinds = False , sdocSuppressUniques = False , sdocSuppressModulePrefixes = False , sdocSuppressStgExts = False , sdocErrorSpans = False , sdocStarIsType = False , sdocImpredicativeTypes = False , sdocLinearTypes = False , sdocPrintTypeAbbreviations = True , sdocUnitIdForUser = ftext } withPprStyle :: PprStyle -> SDoc -> SDoc withPprStyle sty d = SDoc $ \ctxt -> runSDoc d ctxt{sdocStyle=sty} pprDeeper :: SDoc -> SDoc pprDeeper d = SDoc $ \ctx -> case sdocStyle ctx of PprUser q depth c -> let deeper 0 = Pretty.text "..." deeper n = runSDoc d ctx{sdocStyle = PprUser q (PartWay (n-1)) c} in case depth of DefaultDepth -> deeper (sdocDefaultDepth ctx) PartWay n -> deeper n AllTheWay -> runSDoc d ctx _ -> 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 depth c} | DefaultDepth <- depth = work (ctx { sdocStyle = PprUser q (PartWay (sdocDefaultDepth ctx)) c }) | PartWay 0 <- depth = Pretty.text "..." | PartWay n <- depth = let go _ [] = [] go i (d:ds) | i >= n = [text "...."] | otherwise = d : go (i+1) ds in runSDoc (f (go 0 ds)) ctx{sdocStyle = PprUser q (PartWay (n-1)) c} 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 sdocWithContext :: (SDocContext -> SDoc) -> SDoc sdocWithContext f = SDoc $ \ctx -> runSDoc (f ctx) ctx sdocOption :: (SDocContext -> a) -> (a -> SDoc) -> SDoc sdocOption f g = sdocWithContext (g . f) updSDocContext :: (SDocContext -> SDocContext) -> SDoc -> SDoc updSDocContext upd doc = SDoc $ \ctx -> runSDoc doc (upd 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 userStyle :: PprStyle -> Bool userStyle (PprUser {}) = True userStyle _other = False -- | Indicate if -dppr-debug mode is enabled getPprDebug :: (Bool -> SDoc) -> SDoc getPprDebug d = sdocWithContext $ \ctx -> d (sdocPprDebug ctx) -- | Says what to do with and without -dppr-debug ifPprDebug :: SDoc -> SDoc -> SDoc ifPprDebug yes no = getPprDebug $ \dbg -> if dbg then yes else no -- | Says what to do with -dppr-debug; without, return empty whenPprDebug :: SDoc -> SDoc -- Empty for non-debug style 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 :: SDocContext -> Mode -> Handle -> SDoc -> IO () printSDoc ctx mode handle doc = Pretty.printDoc_ mode cols handle (runSDoc doc ctx) `finally` Pretty.printDoc_ mode cols handle (runSDoc (coloured Col.colReset empty) ctx) where cols = sdocLineLength ctx -- | Like 'printSDoc' but appends an extra newline. printSDocLn :: SDocContext -> Mode -> Handle -> SDoc -> IO () printSDocLn ctx mode handle doc = printSDoc ctx mode handle (doc $$ text "") -- | An efficient variant of 'printSDoc' specialized for 'LeftMode' that -- outputs to a 'BufHandle'. bufLeftRenderSDoc :: SDocContext -> BufHandle -> SDoc -> IO () bufLeftRenderSDoc ctx bufHandle doc = Pretty.bufLeftRender bufHandle (runSDoc doc ctx) pprCode :: LabelStyle -> SDoc -> SDoc pprCode cs d = withPprStyle (PprCode cs) d renderWithContext :: SDocContext -> SDoc -> String renderWithContext ctx sdoc = let s = Pretty.style{ Pretty.mode = PageMode False, Pretty.lineLength = sdocLineLength ctx } in Pretty.renderStyle s $ runSDoc sdoc ctx -- 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 :: SDocContext -> SDoc -> String showSDocOneLine ctx d = let s = Pretty.style{ Pretty.mode = OneLineMode, Pretty.lineLength = sdocLineLength ctx } in Pretty.renderStyle s $ runSDoc d ctx showSDocUnsafe :: SDoc -> String showSDocUnsafe sdoc = renderWithContext defaultSDocContext sdoc showPprUnsafe :: Outputable a => a -> String showPprUnsafe a = renderWithContext defaultSDocContext (ppr a) isEmpty :: SDocContext -> SDoc -> Bool isEmpty ctx sdoc = Pretty.isEmpty $ runSDoc sdoc (ctx {sdocPprDebug = True}) 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 -- See Note [Print Hexadecimal Literals] in GHC.Utils.Ppr word n = sdocOption sdocHexWordLiterals $ \case True -> docToSDoc $ Pretty.hex n False -> 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 = sdocOption sdocCanUseUnicode $ \case True -> char '‘' <> d <> char '’' False -> SDoc $ \sty -> let pp_d = runSDoc d sty str = show pp_d in case str of [] -> Pretty.quotes pp_d '\'' : _ -> pp_d _ | '\'' <- last str -> pp_d | otherwise -> Pretty.quotes pp_d semi, comma, colon, equals, space, dcolon, underscore, dot, vbar :: SDoc arrow, lollipop, larrow, darrow, arrowt, larrowt, arrowtt, larrowtt, lambda :: 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 "->") lollipop = unicodeSyntax (char '⊸') (docToSDoc $ Pretty.text "%1 ->") 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 "-<<") lambda = unicodeSyntax (char 'λ') (char '\\') 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 mulArrow :: SDoc -> SDoc mulArrow d = text "%" <> d <+> arrow forAllLit :: SDoc forAllLit = unicodeSyntax (char '∀') (text "forall") bullet :: SDoc bullet = unicode (char '•') (char '*') unicodeSyntax :: SDoc -> SDoc -> SDoc unicodeSyntax unicode plain = sdocOption sdocCanUseUnicode $ \can_use_unicode -> sdocOption sdocPrintUnicodeSyntax $ \print_unicode_syntax -> if can_use_unicode && print_unicode_syntax then unicode else plain unicode :: SDoc -> SDoc -> SDoc unicode unicode plain = sdocOption sdocCanUseUnicode $ \case True -> unicode False -> 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 ppWhenOption :: (SDocContext -> Bool) -> SDoc -> SDoc ppWhenOption f doc = sdocOption f $ \case True -> doc False -> empty ppUnlessOption :: (SDocContext -> Bool) -> SDoc -> SDoc ppUnlessOption f doc = sdocOption f $ \case True -> empty False -> doc -- | Apply the given colour\/style for the argument. -- -- Only takes effect if colours are enabled. coloured :: Col.PprColour -> SDoc -> SDoc coloured col sdoc = sdocOption sdocShouldUseColor $ \case True -> SDoc $ \case ctx@SDC{ sdocLastColour = lastCol, 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) ctx -> runSDoc sdoc ctx False -> sdoc keyword :: SDoc -> SDoc keyword = coloured Col.colBold ----------------------------------------------------------------------- -- The @Outputable@ class ----------------------------------------------------------------------- -- | Class designating that some type has an 'SDoc' representation class Outputable a where ppr :: a -> SDoc 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 Word64 where ppr n = integer $ fromIntegral n instance Outputable Word where ppr n = integer $ fromIntegral n instance Outputable Float where ppr f = float f instance Outputable Double where ppr f = double f instance Outputable () where ppr _ = text "()" instance (Outputable a) => Outputable [a] where ppr xs = brackets (fsep (punctuate comma (map ppr xs))) instance (Outputable a) => Outputable (NonEmpty a) where ppr = ppr . NEL.toList instance (Outputable a) => Outputable (Set a) where ppr s = braces (fsep (punctuate comma (map ppr (Set.toList s)))) instance Outputable IntSet.IntSet where ppr s = braces (fsep (punctuate comma (map ppr (IntSet.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 ppr Nothing = text "Nothing" ppr (Just x) = text "Just" <+> ppr x instance (Outputable a, Outputable b) => Outputable (Either a b) where ppr (Left x) = text "Left" <+> ppr x ppr (Right y) = text "Right" <+> ppr y -- ToDo: may not be used instance (Outputable a, Outputable b, Outputable c) => Outputable (a, b, c) where ppr (x,y,z) = parens (sep [ppr x <> comma, ppr y <> comma, ppr z ]) instance (Outputable a, Outputable b, Outputable c, Outputable d) => Outputable (a, b, c, d) where ppr (a,b,c,d) = parens (sep [ppr a <> comma, ppr b <> comma, ppr c <> comma, ppr d]) instance (Outputable a, Outputable b, Outputable c, Outputable d, Outputable e) => Outputable (a, b, c, d, e) where ppr (a,b,c,d,e) = parens (sep [ppr a <> comma, ppr b <> comma, ppr c <> comma, ppr d <> comma, ppr e]) instance (Outputable a, Outputable b, Outputable c, Outputable d, Outputable e, Outputable f) => Outputable (a, b, c, d, e, f) where ppr (a,b,c,d,e,f) = parens (sep [ppr a <> comma, ppr b <> comma, ppr c <> comma, ppr d <> comma, ppr e <> comma, ppr f]) instance (Outputable a, Outputable b, Outputable c, Outputable d, Outputable e, Outputable f, Outputable g) => Outputable (a, b, c, d, e, f, g) where ppr (a,b,c,d,e,f,g) = parens (sep [ppr a <> comma, ppr b <> comma, ppr c <> comma, ppr d <> comma, ppr e <> comma, ppr f <> comma, ppr g]) instance Outputable FastString where ppr fs = ftext fs -- Prints an unadorned string, -- no double quotes or anything deriving newtype instance Outputable NonDetFastString deriving newtype instance Outputable LexicalFastString instance (Outputable key, Outputable elt) => Outputable (M.Map key elt) where ppr m = ppr (M.toList m) instance (Outputable elt) => Outputable (IM.IntMap elt) where ppr m = ppr (IM.toList m) instance Outputable Fingerprint where ppr (Fingerprint w1 w2) = text (printf "%016x%016x" w1 w2) instance Outputable a => Outputable (SCC a) where ppr (AcyclicSCC v) = text "NONREC" $$ (nest 3 (ppr v)) ppr (CyclicSCC vs) = text "REC" $$ (nest 3 (vcat (map ppr vs))) instance Outputable Serialized where ppr (Serialized the_type bytes) = int (length bytes) <+> text "of type" <+> text (show the_type) instance Outputable Extension where ppr = text . show ----------------------------------------------------------------------- -- The @OutputableP@ class ----------------------------------------------------------------------- -- Note [The OutputableP class] -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -- -- SDoc has become the common type to -- * display messages in the terminal -- * dump outputs (Cmm, Asm, C, etc.) -- * return messages to ghc-api clients -- -- SDoc is a kind of state Monad: SDoc ~ State SDocContext Doc -- I.e. to render a SDoc, a SDocContext must be provided. -- -- SDocContext contains legit rendering options (e.g., line length, color and -- unicode settings). Sadly SDocContext ended up also being used to thread -- values that were considered bothersome to thread otherwise: -- * current HomeModule: to decide if module names must be printed qualified -- * current UnitState: to print unit-ids as "packagename-version:component" -- * target platform: to render labels, instructions, etc. -- * selected backend: to display CLabel as C labels or Asm labels -- -- In fact the whole compiler session state that is DynFlags was passed in -- SDocContext and these values were retrieved from it. -- -- The Outputable class makes SDoc creation easy for many values by providing -- the ppr method: -- -- class Outputable a where -- ppr :: a -> SDoc -- -- Almost every type is Outputable in the compiler and it seems great because it -- is similar to the Show class. But it's a fallacious simplicity because `SDoc` -- needs a `SDocContext` to be transformed into a renderable `Doc`: who is going -- to provide the SDocContext with the correct values in it? -- -- E.g. if a SDoc is returned in an exception, how could we know the home -- module at the time it was thrown? -- -- A workaround is to pass dummy values (no home module, empty UnitState) at SDoc -- rendering time and to hope that the code that produced the SDoc has updated -- the SDocContext with meaningful values (e.g. using withPprStyle or -- pprWithUnitState). If the context isn't correctly updated, a dummy value is -- used and the printed result isn't what we expected. Note that the compiler -- doesn't help us finding spots where we need to update the SDocContext. -- -- In some cases we can't pass a dummy value because we can't create one. For -- example, how can we create a dummy Platform value? In the old days, GHC only -- supported a single Platform set when it was built, so we could use it without -- any risk of mistake. But now GHC starts supporting several Platform in the -- same session so it becomes an issue. We could be tempted to use the -- workaround described above by using "undefined" as a dummy Platform value. -- However in this case, if we forget to update it we will get a runtime -- error/crash. We could use "Maybe Platform" and die with a better error -- message at places where we really really need to know if we are on Windows or -- not, or if we use 32- or 64-bit. Still the compiler would not help us in -- finding spots where to update the context with a valid Platform. -- -- So finally here comes the OutputableP class: -- -- class OutputableP env a where -- pdoc :: env -> a -> SDoc -- -- OutputableP forces us to thread an environment necessary to print a value. -- For now we only use it to thread a Platform environment, so we have several -- "Outputable Platform XYZ" instances. In the future we could imagine using a -- Has class to retrieve a value from a generic environment to make the code -- more composable. E.g.: -- -- instance Has Platform env => OutputableP env XYZ where -- pdoc env a = ... (getter env :: Platform) -- -- A drawback of this approach over Outputable is that we have to thread an -- environment explicitly to use "pdoc" and it's more cumbersome. But it's the -- price to pay to have some help from the compiler to ensure that we... thread -- an environment down to the places where we need it, i.e. where SDoc are -- created (not rendered). On the other hand, it makes life easier for SDoc -- renderers as they only have to deal with pretty-printing related options in -- SDocContext. -- -- TODO: -- -- 1) we could use OutputableP to thread a UnitState and replace the Outputable -- instance of UnitId with: -- -- instance OutputableP UnitState UnitId where ... -- -- This would allow the removal of the `sdocUnitIdForUser` field. -- -- Be warned: I've tried to do it, but there are A LOT of other Outputable -- instances depending on UnitId's one. In particular: -- UnitId <- Unit <- Module <- Name <- Var <- Core.{Type,Expr} <- ... -- -- 2) Use it to pass the HomeModule (but I fear it will be as difficult as for -- UnitId). -- -- -- | Outputable class with an additional environment value -- -- See Note [The OutputableP class] class OutputableP env a where pdoc :: env -> a -> SDoc -- | Wrapper for types having a Outputable instance when an OutputableP instance -- is required. newtype PDoc a = PDoc a instance Outputable a => OutputableP env (PDoc a) where pdoc _ (PDoc a) = ppr a instance OutputableP env a => OutputableP env [a] where pdoc env xs = ppr (fmap (pdoc env) xs) instance OutputableP env a => OutputableP env (Maybe a) where pdoc env xs = ppr (fmap (pdoc env) xs) instance (OutputableP env a, OutputableP env b) => OutputableP env (a, b) where pdoc env (a,b) = ppr (pdoc env a, pdoc env b) instance (OutputableP env a, OutputableP env b, OutputableP env c) => OutputableP env (a, b, c) where pdoc env (a,b,c) = ppr (pdoc env a, pdoc env b, pdoc env c) instance (OutputableP env key, OutputableP env elt) => OutputableP env (M.Map key elt) where pdoc env m = ppr $ fmap (\(x,y) -> (pdoc env x, pdoc env y)) $ M.toList m instance OutputableP env a => OutputableP env (SCC a) where pdoc env scc = ppr (fmap (pdoc env) scc) instance OutputableP env SDoc where pdoc _ x = x instance (OutputableP env a) => OutputableP env (Set a) where pdoc env s = braces (fsep (punctuate comma (map (pdoc env) (Set.toList s)))) {- ************************************************************************ * * \subsection{The @OutputableBndr@ class} * * ************************************************************************ -} -- | 'BindingSite' is used to tell the thing that prints binder what -- language construct is binding the identifier. This can be used -- to decide how much info to print. -- Also see Note [Binding-site specific printing] in "GHC.Core.Ppr" data BindingSite = LambdaBind -- ^ The x in (\x. e) | CaseBind -- ^ The x in case scrut of x { (y,z) -> ... } | CasePatBind -- ^ The y,z in case scrut of x { (y,z) -> ... } | LetBind -- ^ The x in (let x = rhs in e) -- | When we print a binder, we often want to print its type too. -- The @OutputableBndr@ class encapsulates this idea. class Outputable a => OutputableBndr a where pprBndr :: BindingSite -> a -> SDoc pprBndr _b x = ppr x pprPrefixOcc, pprInfixOcc :: a -> SDoc -- Print an occurrence of the name, suitable either in the -- prefix position of an application, thus (f a b) or ((+) x) -- or infix position, thus (a `f` b) or (x + y) bndrIsJoin_maybe :: a -> Maybe Int bndrIsJoin_maybe _ = Nothing -- When pretty-printing we sometimes want to find -- whether the binder is a join point. You might think -- we could have a function of type (a->Var), but Var -- isn't available yet, alas {- ************************************************************************ * * \subsection{Random printing helpers} * * ************************************************************************ -} -- We have 31-bit Chars and will simply use Show instances of Char and String. -- | Special combinator for showing character literals. pprHsChar :: Char -> SDoc pprHsChar c | c > '\x10ffff' = char '\\' <> text (show (fromIntegral (ord c) :: Word32)) | otherwise = text (show c) -- | Special combinator for showing string literals. pprHsString :: FastString -> SDoc pprHsString fs = vcat (map text (showMultiLineString (unpackFS fs))) -- | Special combinator for showing bytestring literals. pprHsBytes :: ByteString -> SDoc pprHsBytes bs = let escaped = concatMap escape $ BS.unpack bs in vcat (map text (showMultiLineString escaped)) <> char '#' where escape :: Word8 -> String escape w = let c = chr (fromIntegral w) in if isAscii c then [c] else '\\' : show w -- Postfix modifiers for unboxed literals. -- See Note [Printing of literals in Core] in "GHC.Types.Literal". primCharSuffix, primFloatSuffix, primDoubleSuffix, primIntSuffix, primWordSuffix, primInt8Suffix, primWord8Suffix, primInt16Suffix, primWord16Suffix, primInt32Suffix, primWord32Suffix, primInt64Suffix, primWord64Suffix :: SDoc primCharSuffix = char '#' primFloatSuffix = char '#' primIntSuffix = char '#' primDoubleSuffix = text "##" primWordSuffix = text "##" primInt8Suffix = text "#8" primWord8Suffix = text "##8" primInt16Suffix = text "#16" primWord16Suffix = text "##16" primInt32Suffix = text "#32" primWord32Suffix = text "##32" primInt64Suffix = text "#64" primWord64Suffix = text "##64" -- | Special combinator for showing unboxed literals. pprPrimChar :: Char -> SDoc pprPrimInt, pprPrimWord, pprPrimInt8, pprPrimWord8, pprPrimInt16, pprPrimWord16, pprPrimInt32, pprPrimWord32, pprPrimInt64, pprPrimWord64 :: Integer -> SDoc pprPrimChar c = pprHsChar c <> primCharSuffix pprPrimInt i = integer i <> primIntSuffix pprPrimWord w = word w <> primWordSuffix pprPrimInt8 i = integer i <> primInt8Suffix pprPrimInt16 i = integer i <> primInt16Suffix pprPrimInt32 i = integer i <> primInt32Suffix pprPrimInt64 i = integer i <> primInt64Suffix pprPrimWord8 w = word w <> primWord8Suffix pprPrimWord16 w = word w <> primWord16Suffix pprPrimWord32 w = word w <> primWord32Suffix pprPrimWord64 w = word w <> primWord64Suffix --------------------- -- Put a name in parens if it's an operator pprPrefixVar :: Bool -> SDoc -> SDoc pprPrefixVar is_operator pp_v | is_operator = parens pp_v | otherwise = pp_v -- Put a name in backquotes if it's not an operator pprInfixVar :: Bool -> SDoc -> SDoc pprInfixVar is_operator pp_v | is_operator = pp_v | otherwise = char '`' <> pp_v <> char '`' --------------------- pprFastFilePath :: FastString -> SDoc pprFastFilePath path = text $ normalise $ unpackFS path -- | Normalise, escape and render a string representing a path -- -- e.g. "c:\\whatever" pprFilePathString :: FilePath -> SDoc pprFilePathString path = doubleQuotes $ text (escape (normalise path)) where escape [] = [] escape ('\\':xs) = '\\':'\\':escape xs escape (x:xs) = x:escape xs {- ************************************************************************ * * \subsection{Other helper functions} * * ************************************************************************ -} pprWithCommas :: (a -> SDoc) -- ^ The pretty printing function to use -> [a] -- ^ The things to be pretty printed -> SDoc -- ^ 'SDoc' where the things have been pretty printed, -- comma-separated and finally packed into a paragraph. pprWithCommas pp xs = fsep (punctuate comma (map pp xs)) pprWithBars :: (a -> SDoc) -- ^ The pretty printing function to use -> [a] -- ^ The things to be pretty printed -> SDoc -- ^ 'SDoc' where the things have been pretty printed, -- bar-separated and finally packed into a paragraph. pprWithBars pp xs = fsep (intersperse vbar (map pp xs)) -- | Returns the separated concatenation of the pretty printed things. interppSP :: Outputable a => [a] -> SDoc interppSP xs = sep (map ppr xs) -- | Returns the comma-separated concatenation of the pretty printed things. interpp'SP :: Outputable a => [a] -> SDoc interpp'SP xs = interpp'SP' ppr xs interpp'SP' :: (a -> SDoc) -> [a] -> SDoc interpp'SP' f xs = sep (punctuate comma (map f xs)) -- | Returns the comma-separated concatenation of the quoted pretty printed things. -- -- > [x,y,z] ==> `x', `y', `z' pprQuotedList :: Outputable a => [a] -> SDoc pprQuotedList = quotedList . map ppr quotedList :: [SDoc] -> SDoc quotedList xs = fsep (punctuate comma (map quotes xs)) quotedListWithOr :: [SDoc] -> SDoc -- [x,y,z] ==> `x', `y' or `z' quotedListWithOr xs@(_:_:_) = quotedList (init xs) <+> text "or" <+> quotes (last xs) quotedListWithOr xs = quotedList xs quotedListWithNor :: [SDoc] -> SDoc -- [x,y,z] ==> `x', `y' nor `z' quotedListWithNor xs@(_:_:_) = quotedList (init xs) <+> text "nor" <+> quotes (last xs) quotedListWithNor xs = quotedList xs {- ************************************************************************ * * \subsection{Printing numbers verbally} * * ************************************************************************ -} intWithCommas :: Integral a => a -> SDoc -- Prints a big integer with commas, eg 345,821 intWithCommas n | n < 0 = char '-' <> intWithCommas (-n) | q == 0 = int (fromIntegral r) | otherwise = intWithCommas q <> comma <> zeroes <> int (fromIntegral r) where (q,r) = n `quotRem` 1000 zeroes | r >= 100 = empty | r >= 10 = char '0' | otherwise = text "00" -- | Converts an integer to a verbal index: -- -- > speakNth 1 = text "first" -- > speakNth 5 = text "fifth" -- > speakNth 21 = text "21st" speakNth :: Int -> SDoc speakNth 1 = text "first" speakNth 2 = text "second" speakNth 3 = text "third" speakNth 4 = text "fourth" speakNth 5 = text "fifth" speakNth 6 = text "sixth" speakNth n = hcat [ int n, text suffix ] where suffix | n <= 20 = "th" -- 11,12,13 are non-std | last_dig == 1 = "st" | last_dig == 2 = "nd" | last_dig == 3 = "rd" | otherwise = "th" last_dig = n `rem` 10 -- | Converts an integer to a verbal multiplicity: -- -- > speakN 0 = text "none" -- > speakN 5 = text "five" -- > speakN 10 = text "10" speakN :: Int -> SDoc speakN 0 = text "none" -- E.g. "they have none" speakN 1 = text "one" -- E.g. "they have one" speakN 2 = text "two" speakN 3 = text "three" speakN 4 = text "four" speakN 5 = text "five" speakN 6 = text "six" speakN n = int n -- | Converts an integer and object description to a statement about the -- multiplicity of those objects: -- -- > speakNOf 0 (text "melon") = text "no melons" -- > speakNOf 1 (text "melon") = text "one melon" -- > speakNOf 3 (text "melon") = text "three melons" speakNOf :: Int -> SDoc -> SDoc speakNOf 0 d = text "no" <+> d <> char 's' speakNOf 1 d = text "one" <+> d -- E.g. "one argument" speakNOf n d = speakN n <+> d <> char 's' -- E.g. "three arguments" -- | Determines the pluralisation suffix appropriate for the length of a list: -- -- > plural [] = char 's' -- > plural ["Hello"] = empty -- > plural ["Hello", "World"] = char 's' plural :: [a] -> SDoc plural [_] = empty -- a bit frightening, but there you are plural _ = char 's' -- | Determines the form of to be appropriate for the length of a list: -- -- > isOrAre [] = text "are" -- > isOrAre ["Hello"] = text "is" -- > isOrAre ["Hello", "World"] = text "are" isOrAre :: [a] -> SDoc isOrAre [_] = text "is" isOrAre _ = text "are" -- | Determines the form of to do appropriate for the length of a list: -- -- > doOrDoes [] = text "do" -- > doOrDoes ["Hello"] = text "does" -- > doOrDoes ["Hello", "World"] = text "do" doOrDoes :: [a] -> SDoc doOrDoes [_] = text "does" doOrDoes _ = text "do" -- | Determines the form of possessive appropriate for the length of a list: -- -- > itsOrTheir [x] = text "its" -- > itsOrTheir [x,y] = text "their" -- > itsOrTheir [] = text "their" -- probably avoid this itsOrTheir :: [a] -> SDoc itsOrTheir [_] = text "its" itsOrTheir _ = text "their"