Text.PrettyPrint

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.

This module should be used as opposed to the HughesPJ module. Both are equivalent though as this module simply re-exports the other.

The document type

data Doc

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

Eq Doc

Methods

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

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

Show Doc

Methods

showsPrec :: Int -> Doc -> ShowS

show :: Doc -> String

showList :: [Doc] -> ShowS

IsString Doc

Methods

fromString :: String -> Doc

Generic Doc

Associated Types

type Rep Doc :: * -> *

Methods

from :: Doc -> Rep Doc x

to :: Rep Doc x -> Doc

Semigroup Doc

Methods

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

sconcat :: NonEmpty Doc -> Doc

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

Monoid Doc

Methods

mempty :: Doc

mappend :: Doc -> Doc -> Doc

mconcat :: [Doc] -> Doc

NFData Doc

Methods

rnf :: Doc -> ()

type Rep Doc

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

Constructing documents

Converting values into documents

char :: Char -> Doc

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

text :: String -> Doc

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

• text s <> text t = text (s++t)

• text "" <> x = x, if x non-empty

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

ptext :: String -> Doc

Same as text. Used to be used for Bytestrings.

sizedText :: Int -> String -> Doc

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

zeroWidthText :: String -> Doc

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

int

Arguments

:: Int

-> Doc

int n = text (show n)

integer

Arguments

:: Integer

-> Doc

integer n = text (show n)

float

Arguments

:: Float

-> Doc

float n = text (show n)

double

Arguments

:: Double

-> Doc

double n = text (show n)

rational

Arguments

:: Rational

-> Doc

rational n = text (show n)

Simple derived documents

semi

Arguments

:: Doc

A ';' character

comma

Arguments

:: Doc

A ',' character

colon

Arguments

:: Doc

A : character

space

Arguments

:: Doc

A space character

equals

Arguments

:: Doc

A '=' character

lparen

Arguments

:: Doc

A '(' character

rparen

Arguments

:: Doc

A ')' character

lbrack

Arguments

:: Doc

A '[' character

rbrack

Arguments

:: Doc

A ']' character

lbrace

Arguments

:: Doc

A '{' character

rbrace

Arguments

:: Doc

A '}' character

Wrapping documents in delimiters

parens

Arguments

:: Doc

-> Doc

Wrap document in (...)

brackets

Arguments

:: Doc

-> Doc

Wrap document in [...]

braces

Arguments

:: Doc

-> Doc

Wrap document in {...}

quotes

Arguments

:: Doc

-> Doc

Wrap document in '...'

doubleQuotes

Arguments

:: Doc

-> Doc

Wrap document in "..."

Combining documents

empty :: Doc

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

Beside. <> is associative, with identity empty.

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

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

hcat :: [Doc] -> Doc

List version of <>.

hsep :: [Doc] -> Doc

List version of <+>.

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

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

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

vcat :: [Doc] -> Doc

List version of $$.

sep :: [Doc] -> Doc

Either hsep or vcat.

cat :: [Doc] -> Doc

Either hcat or vcat.

fsep :: [Doc] -> Doc

"Paragraph fill" version of sep.

fcat :: [Doc] -> Doc

"Paragraph fill" version of cat.

nest :: Int -> Doc -> Doc

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

• nest 0 x = x

• nest k (nest k' x) = nest (k+k') x

• nest k (x <> y) = nest k x <> nest k y

• nest k (x $$ y) = nest k x $$ nest k y

• nest k empty = empty

• x <> nest k y = x <> y, if x non-empty

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

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

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

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

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

Predicates on documents

isEmpty :: Doc -> Bool

Returns True if the document is empty

Rendering documents

Default rendering

render :: Doc -> String

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

Rendering with a particular style

data Style

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

Eq Style

Methods

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

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

Show Style

Methods

showsPrec :: Int -> Style -> ShowS

show :: Style -> String

showList :: [Style] -> ShowS

Generic Style

Associated Types

type Rep Style :: * -> *

Methods

from :: Style -> Rep Style x

to :: Rep Style x -> Style

type Rep Style

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

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

renderStyle :: Style -> Doc -> String

Render the Doc to a String using the given Style.

General rendering

fullRender

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.

data 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.

Instances

Eq Mode

Methods

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

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

Show Mode

Methods

showsPrec :: Int -> Mode -> ShowS

show :: Mode -> String

showList :: [Mode] -> ShowS

Generic Mode

Associated Types

type Rep Mode :: * -> *

Methods

from :: Mode -> Rep Mode x

to :: Rep Mode x -> Mode

type Rep Mode

type Rep Mode = D1 (MetaData "Mode" "Text.PrettyPrint.Annotated.HughesPJ" "pretty-1.1.3.6-inplace" 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 :: * -> *)))

data TextDetails

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.

Instances

Eq TextDetails

Methods

(==) :: TextDetails -> TextDetails -> Bool

(/=) :: TextDetails -> TextDetails -> Bool

Show TextDetails

Methods

showsPrec :: Int -> TextDetails -> ShowS

show :: TextDetails -> String

showList :: [TextDetails] -> ShowS

Generic TextDetails

Associated Types

type Rep TextDetails :: * -> *

Methods

from :: TextDetails -> Rep TextDetails x

to :: Rep TextDetails x -> TextDetails

NFData TextDetails

Methods

rnf :: TextDetails -> ()

type Rep TextDetails

type Rep TextDetails = D1 (MetaData "TextDetails" "Text.PrettyPrint.Annotated.HughesPJ" "pretty-1.1.3.6-inplace" False) (C1 (MetaCons "Chr" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) SourceUnpack SourceStrict DecidedStrict) (Rec0 Char)) :+: (C1 (MetaCons "Str" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 String)) :+: C1 (MetaCons "PStr" PrefixI False) (S1 (MetaSel (Nothing :: Maybe Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 String))))