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GHC 10.0.0.20260917 · lts/ghc-10.0.x · 8fef28d · 2026-11-02

Modulehaskell-src-1.0.4.2Haskell98

Language.Haskell.Pretty

Pretty printer for Haskell.

Contents

Pretty printing
Pretty-printing styles (from Text.PrettyPrint.HughesPJ)
Haskell formatting modes

Synopsis

class Pretty
value prettyPrintStyleMode
value prettyPrintWithMode
value prettyPrint
data Style
value style
data Mode
data PPHsMode
type Indent
data PPLayout
value defaultMode

Packagehaskell-src-1.0.4.2
Exports11
LanguageHaskell98
LicenceBSD-3-Clause
SourcePretty.hs

Pretty printing

classclass Pretty a where

Things that can be pretty-printed, including all the syntactic objects in Language.Haskell.Syntax.

Instances29Pretty, …

Pretty HsAltDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsAssocDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsBangTypeDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsCNameDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsConDeclDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsDeclDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsExpDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsExportSpecDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsFieldUpdateDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsGuardedAltDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsGuardedAltsDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsGuardedRhsDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsImportDeclDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsImportSpecDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsLiteralDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsMatchDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsModuleDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsNameDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsOpDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsPatDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsPatFieldDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsQNameDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsQOpDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsQualTypeDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsRhsDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsSafetyDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsStmtDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty HsTypeDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty
Pretty ModuleDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty

valueprettyPrintStyleMode :: Pretty a => Style -> PPHsMode -> a -> String

pretty-print with a given style and mode.

valueprettyPrintWithMode :: Pretty a => PPHsMode -> a -> String

pretty-print with the default style and a given mode.

valueprettyPrint :: Pretty a => a -> String

pretty-print with the default style and defaultMode.

Pretty-printing styles (from Text.PrettyPrint.HughesPJ)

datadata Style

A rendering style. Allows us to specify constraints to choose among the many different rendering options.

Constructors

Style
- mode :: Mode
  The rendering mode.
- lineLength :: Int
  Maximum length of a line, in characters.
- ribbonsPerLine :: Float
  Ratio of line length to ribbon length. A ribbon refers to the characters on a line excluding indentation. So a lineLength of 100, with a ribbonsPerLine of 2.0 would only allow up to 50 characters of ribbon to be displayed on a line, while allowing it to be indented up to 50 characters.

Instances4Eq, Show, Generic, Rep

Eq StyleDefined in pretty-1.1.3.6 · Text.PrettyPrint.Annotated.HughesPJ
Show StyleDefined in pretty-1.1.3.6 · Text.PrettyPrint.Annotated.HughesPJ
Generic StyleDefined in pretty-1.1.3.6 · Text.PrettyPrint.Annotated.HughesPJ
type Rep Style = D1 ('MetaData "Style" "Text.PrettyPrint.Annotated.HughesPJ" "pretty-1.1.3.6-f8d5" 'False) (C1 ('MetaCons "Style" 'PrefixI 'True) (S1 ('MetaSel ('Just "mode") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Mode) :*: (S1 ('MetaSel ('Just "lineLength") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Int) :*: S1 ('MetaSel ('Just "ribbonsPerLine") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 Float))))Defined in pretty-1.1.3.6 · Text.PrettyPrint.Annotated.HughesPJ

valuestyle :: Style

The default style (mode=PageMode, lineLength=100, ribbonsPerLine=1.5).

datadata Mode

Rendering mode.

Constructors

PageMode
Normal rendering (lineLength and ribbonsPerLine respected').
ZigZagMode
With zig-zag cuts.
LeftMode
No indentation, infinitely long lines (lineLength ignored), but explicit new lines, i.e., text "one" $$ text "two", are respected.
OneLineMode
All on one line, lineLength ignored and explicit new lines ($$) are turned into spaces.

Instances4Eq, Show, Generic, Rep

Eq ModeDefined in pretty-1.1.3.6 · Text.PrettyPrint.Annotated.HughesPJ
Show ModeDefined in pretty-1.1.3.6 · Text.PrettyPrint.Annotated.HughesPJ
Generic ModeDefined in pretty-1.1.3.6 · Text.PrettyPrint.Annotated.HughesPJ
type Rep Mode = D1 ('MetaData "Mode" "Text.PrettyPrint.Annotated.HughesPJ" "pretty-1.1.3.6-f8d5" 'False) ((C1 ('MetaCons "PageMode" 'PrefixI 'False) U1 :+: C1 ('MetaCons "ZigZagMode" 'PrefixI 'False) U1) :+: (C1 ('MetaCons "LeftMode" 'PrefixI 'False) U1 :+: C1 ('MetaCons "OneLineMode" 'PrefixI 'False) U1))Defined in pretty-1.1.3.6 · Text.PrettyPrint.Annotated.HughesPJ

Haskell formatting modes

datadata PPHsMode

Pretty-printing parameters.

Note: the onsideIndent must be positive and less than all other indents.

Constructors

PPHsMode
- classIndent :: Indent
  Indentation of a class or instance.
- doIndent :: Indent
  Indentation of a do-expression.
- caseIndent :: Indent
  Indentation of the body of a case expression.
- letIndent :: Indent
  Indentation of the declarations in a let expression.
- whereIndent :: Indent
  Indentation of the declarations in a where clause.
- onsideIndent :: Indent
  Indentation added for continuation lines that would otherwise be offside.
- spacing :: Bool
  Blank lines between statements?
- layout :: PPLayout
  Pretty-printing style to use.
- linePragmas :: Bool
  Add GHC-style LINE pragmas to output?
- comments :: Bool
  (not implemented yet)

typetype Indent = Int

datadata PPLayout

Varieties of layout we can use.

Constructors

PPOffsideRule
Classical layout.
PPSemiColon
Classical layout made explicit.
PPInLine
Inline decls, with newlines between them.
PPNoLayout
Everything on a single line.

Instances1Eq

Eq PPLayoutDefined in haskell-src-1.0.4.2 · Language.Haskell.Pretty

valuedefaultMode :: PPHsMode

The default mode: pretty-print using the offside rule and sensible defaults.