Text.PrettyPrint.HughesPJ

Copyright (c) The University of Glasgow 2001
License BSD-style (see the file LICENSE)
Maintainer David Terei <[email protected]>
Stability stable
Portability portable
Safe Haskell Safe
Language Haskell98

Description

Provides a collection of pretty printer combinators, a set of API's that provides a way to easily print out text in a consistent format of your choosing.

Originally designed by John Hughes's and Simon Peyton Jones's.

For more information you can refer to the original paper that serves as the basis for this libraries design: /The Design of a Pretty-printing Library/ by John Hughes, in Advanced Functional Programming, 1995.

The document type

data Doc Source

The abstract type of documents. A Doc represents a set of layouts. A Doc with no occurrences of Union or NoDoc represents just one layout.

Instances
Instances details
Eq Doc
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Methods

(==) :: Doc -> Doc -> Bool Source

(/=) :: Doc -> Doc -> Bool Source

Show Doc
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Methods

showsPrec :: Int -> Doc -> ShowS Source

show :: Doc -> String Source

showList :: [Doc] -> ShowS Source

IsString Doc
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Methods

fromString :: String -> Doc Source

Generic Doc
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Associated Types

type Rep Doc :: Type -> Type Source

Methods

from :: Doc -> Rep Doc x Source

to :: Rep Doc x -> Doc Source

Semigroup Doc
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Methods

(<>) :: Doc -> Doc -> Doc Source

sconcat :: NonEmpty Doc -> Doc Source

stimes :: Integral b => b -> Doc -> Doc Source

Monoid Doc
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Methods

mempty :: Doc Source

mappend :: Doc -> Doc -> Doc Source

mconcat :: [Doc] -> Doc Source

NFData Doc
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Methods

rnf :: Doc -> () Source

type Rep Doc
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Defined in Text.PrettyPrint.HughesPJ

type Rep Doc = D1 ('MetaData "Doc" "Text.PrettyPrint.HughesPJ" "pretty-1.1.3.6" 'True) (C1 ('MetaCons "Doc" 'PrefixI 'False) (S1 ('MetaSel ('Nothing :: Maybe Symbol) 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 (Doc ()))))

data TextDetails Source

A TextDetails represents a fragment of text that will be output at some point in a Doc.

Constructors

Chr !Char

A single Char fragment

Str String

A whole String fragment

PStr String

Used to represent a Fast String fragment but now deprecated and identical to the Str constructor.

Constructing documents

Converting values into documents

char :: Char -> Doc Source

A document of height and width 1, containing a literal character.

text :: String -> Doc Source

A document of height 1 containing a literal string. text satisfies the following laws:

The side condition on the last law is necessary because text "" has height 1, while empty has no height.

ptext :: String -> Doc Source

Same as text. Used to be used for Bytestrings.

sizedText :: Int -> String -> Doc Source

Some text with any width. (text s = sizedText (length s) s)

zeroWidthText :: String -> Doc Source

Some text, but without any width. Use for non-printing text such as a HTML or Latex tags

int Source

Arguments

:: Int
-> Doc
int n = text (show n)

integer Source

Arguments

:: Integer
-> Doc
integer n = text (show n)

float Source

Arguments

:: Float
-> Doc
float n = text (show n)

double Source

Arguments

:: Double
-> Doc
double n = text (show n)

rational Source

Arguments

:: Rational
-> Doc
rational n = text (show n)

Simple derived documents

semi Source

Arguments

:: Doc

A ';' character

comma Source

Arguments

:: Doc

A ',' character

colon Source

Arguments

:: Doc

A : character

space Source

Arguments

:: Doc

A space character

equals Source

Arguments

:: Doc

A '=' character

lparen Source

Arguments

:: Doc

A '(' character

rparen Source

Arguments

:: Doc

A ')' character

lbrack Source

Arguments

:: Doc

A '[' character

rbrack Source

Arguments

:: Doc

A ']' character

lbrace Source

Arguments

:: Doc

A '{' character

rbrace Source

Arguments

:: Doc

A '}' character

Wrapping documents in delimiters

parens Source

Arguments

:: Doc
-> Doc

Wrap document in (...)

brackets Source

Arguments

:: Doc
-> Doc

Wrap document in [...]

braces Source

Arguments

:: Doc
-> Doc

Wrap document in {...}

quotes Source

Arguments

:: Doc
-> Doc

Wrap document in '...'

doubleQuotes Source

Arguments

:: Doc
-> Doc

Wrap document in "..."

maybeParens :: Bool -> Doc -> Doc Source

Apply parens to Doc if boolean is true.

maybeBrackets :: Bool -> Doc -> Doc Source

Apply brackets to Doc if boolean is true.

maybeBraces :: Bool -> Doc -> Doc Source

Apply braces to Doc if boolean is true.

maybeQuotes :: Bool -> Doc -> Doc Source

Apply quotes to Doc if boolean is true.

maybeDoubleQuotes :: Bool -> Doc -> Doc Source

Apply doubleQuotes to Doc if boolean is true.

Combining documents

empty :: Doc Source

The empty document, with no height and no width. empty is the identity for <>, <+>, $$ and $+$, and anywhere in the argument list for sep, hcat, hsep, vcat, fcat etc.

(<>) :: Doc -> Doc -> Doc infixl 6 Source

Beside. <> is associative, with identity empty.

(<+>) :: Doc -> Doc -> Doc infixl 6 Source

Beside, separated by space, unless one of the arguments is empty. <+> is associative, with identity empty.

hcat :: [Doc] -> Doc Source

List version of <>.

hsep :: [Doc] -> Doc Source

List version of <+>.

($$) :: Doc -> Doc -> Doc infixl 5 Source

Above, except that if the last line of the first argument stops at least one position before the first line of the second begins, these two lines are overlapped. For example:

   text "hi" $$ nest 5 (text "there")

lays out as

   hi   there

rather than

   hi
        there

$$ is associative, with identity empty, and also satisfies

  • (x $$ y) <> z = x $$ (y <> z), if y non-empty.

($+$) :: Doc -> Doc -> Doc infixl 5 Source

Above, with no overlapping. $+$ is associative, with identity empty.

vcat :: [Doc] -> Doc Source

List version of $$.

sep :: [Doc] -> Doc Source

Either hsep or vcat.

cat :: [Doc] -> Doc Source

Either hcat or vcat.

fsep :: [Doc] -> Doc Source

"Paragraph fill" version of sep.

fcat :: [Doc] -> Doc Source

"Paragraph fill" version of cat.

nest :: Int -> Doc -> Doc Source

Nest (or indent) a document by a given number of positions (which may also be negative). nest satisfies the laws:

The side condition on the last law is needed because empty is a left identity for <>.

hang :: Doc -> Int -> Doc -> Doc Source

hang d1 n d2 = sep [d1, nest n d2]

punctuate :: Doc -> [Doc] -> [Doc] Source

punctuate p [d1, ... dn] = [d1 <> p, d2 <> p, ... dn-1 <> p, dn]

Predicates on documents

isEmpty :: Doc -> Bool Source

Returns True if the document is empty

Utility functions for documents

first :: Doc -> Doc -> Doc Source

first returns its first argument if it is non-empty, otherwise its second.

reduceDoc :: Doc -> RDoc Source

Perform some simplification of a built up GDoc.

Rendering documents

Default rendering

render :: Doc -> String Source

Render the Doc to a String using the default Style (see style).

Rendering with a particular style

data Style Source

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

Constructors

Style

Fields

  • 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.

Instances
Instances details
Eq Style
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Methods

(==) :: Style -> Style -> Bool Source

(/=) :: Style -> Style -> Bool Source

Show Style
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Generic Style
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Associated Types

type Rep Style :: Type -> Type Source

Methods

from :: Style -> Rep Style x Source

to :: Rep Style x -> Style Source

type Rep Style
Instance details

Defined in Text.PrettyPrint.Annotated.HughesPJ

type Rep Style = D1 ('MetaData "Style" "Text.PrettyPrint.Annotated.HughesPJ" "pretty-1.1.3.6" '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))))

style :: Style Source

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

renderStyle :: Style -> Doc -> String Source

Render the Doc to a String using the given Style.

data Mode Source

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.

Instances
Instances details
Eq Mode
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Methods

(==) :: Mode -> Mode -> Bool Source

(/=) :: Mode -> Mode -> Bool Source

Show Mode
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Generic Mode
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Associated Types

type Rep Mode :: Type -> Type Source

Methods

from :: Mode -> Rep Mode x Source

to :: Rep Mode x -> Mode Source

type Rep Mode
Instance details

Defined in Text.PrettyPrint.Annotated.HughesPJ

type Rep Mode = D1 ('MetaData "Mode" "Text.PrettyPrint.Annotated.HughesPJ" "pretty-1.1.3.6" 'False) ((C1 ('MetaCons "PageMode" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "ZigZagMode" 'PrefixI 'False) (U1 :: Type -> Type)) :+: (C1 ('MetaCons "LeftMode" 'PrefixI 'False) (U1 :: Type -> Type) :+: C1 ('MetaCons "OneLineMode" 'PrefixI 'False) (U1 :: Type -> Type)))

General rendering

fullRender Source

Arguments

:: Mode

Rendering mode.

-> Int

Line length.

-> Float

Ribbons per line.

-> (TextDetails -> a -> a)

What to do with text.

-> a

What to do at the end.

-> Doc

The document.

-> a

Result.

The general rendering interface. Please refer to the Style and Mode types for a description of rendering mode, line length and ribbons.

© The University of Glasgow and others
Licensed under a BSD-style license (see top of the page).
https://downloads.haskell.org/~ghc/8.10.2/docs/html/libraries/pretty-1.1.3.6/Text-PrettyPrint-HughesPJ.html