Copyright	(c) The University of Glasgow 2001
License	BSD-style (see the file LICENSE)
Maintainer	David Terei <code@davidterei.com>
Stability	stable
Portability	portable
Safe Haskell	Safe
Language	Haskell98

Text.PrettyPrint.HughesPJ

Contents

The document type
Constructing documents
Predicates on documents
Utility functions for documents
Rendering documents

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.

Synopsis

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 Source # (/=) :: Doc -> Doc -> Bool Source #
Show Doc #
Methods showsPrec :: Int -> Doc -> ShowS Source # show :: Doc -> String Source # showList :: [Doc] -> ShowS Source #
IsString Doc #
Methods fromString :: String -> Doc Source #
Generic Doc #
Associated Types type Rep Doc :: * -> * Source # Methods from :: Doc -> Rep Doc x Source # to :: Rep Doc x -> Doc Source #
Semigroup Doc #
Methods (<>) :: Doc -> Doc -> Doc Source # sconcat :: NonEmpty Doc -> Doc Source # stimes :: Integral b => b -> Doc -> Doc Source #
Monoid Doc #
Methods mempty :: Doc Source # mappend :: Doc -> Doc -> Doc Source # mconcat :: [Doc] -> Doc Source #
NFData Doc #
Methods rnf :: Doc -> () Source #
type Rep Doc #
type Rep Doc = D1 (MetaData "Doc" "Text.PrettyPrint.HughesPJ" "pretty-1.1.3.3" True) (C1 (MetaCons "Doc" PrefixI False) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (Doc ()))))

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 Source # (/=) :: TextDetails -> TextDetails -> Bool Source #
Show TextDetails #
Methods showsPrec :: Int -> TextDetails -> ShowS Source # show :: TextDetails -> String Source # showList :: [TextDetails] -> ShowS Source #
Generic TextDetails #
Associated Types type Rep TextDetails :: * -> * Source # Methods from :: TextDetails -> Rep TextDetails x Source # to :: Rep TextDetails x -> TextDetails Source #
NFData TextDetails #
Methods rnf :: TextDetails -> () Source #
type Rep TextDetails #
type Rep TextDetails = D1 (MetaData "TextDetails" "Text.PrettyPrint.Annotated.HughesPJ" "pretty-1.1.3.3" False) ((:+:) (C1 (MetaCons "Chr" PrefixI False) (S1 (MetaSel (Nothing Symbol) SourceUnpack SourceStrict DecidedUnpack) (Rec0 Char))) ((:+:) (C1 (MetaCons "Str" PrefixI False) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 String))) (C1 (MetaCons "PStr" PrefixI False) (S1 (MetaSel (Nothing Symbol) NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 String)))))

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 `"..."`

maybeParens :: Bool -> Doc -> Doc #

Apply parens to Doc if boolean is true.

maybeBrackets :: Bool -> Doc -> Doc #

Apply brackets to Doc if boolean is true.

maybeBraces :: Bool -> Doc -> Doc #

Apply braces to Doc if boolean is true.

maybeQuotes :: Bool -> Doc -> Doc #

Apply quotes to Doc if boolean is true.

maybeDoubleQuotes :: Bool -> Doc -> Doc #

Apply doubleQuotes to Doc if boolean is true.

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 z <> 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

Utility functions for documents

first :: Doc -> Doc -> Doc #

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

reduceDoc :: Doc -> RDoc #

Perform some simplification of a built up GDoc.

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 Source # (/=) :: Style -> Style -> Bool Source #
Show Style #
Methods showsPrec :: Int -> Style -> ShowS Source # show :: Style -> String Source # showList :: [Style] -> ShowS Source #
Generic Style #
Associated Types type Rep Style :: * -> * Source # Methods from :: Style -> Rep Style x Source # to :: Rep Style x -> Style Source #
type Rep Style #
type Rep Style = D1 (MetaData "Style" "Text.PrettyPrint.Annotated.HughesPJ" "pretty-1.1.3.3" False) (C1 (MetaCons "Style" PrefixI True) ((::) (S1 (MetaSel (Just Symbol "mode") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Mode)) ((::) (S1 (MetaSel (Just Symbol "lineLength") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 Int)) (S1 (MetaSel (Just Symbol "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.

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 Source # (/=) :: Mode -> Mode -> Bool Source #
Show Mode #
Methods showsPrec :: Int -> Mode -> ShowS Source # show :: Mode -> String Source # showList :: [Mode] -> ShowS Source #
Generic Mode #
Associated Types type Rep Mode :: * -> * Source # Methods from :: Mode -> Rep Mode x Source # to :: Rep Mode x -> Mode Source #
type Rep Mode #
type Rep Mode = D1 (MetaData "Mode" "Text.PrettyPrint.Annotated.HughesPJ" "pretty-1.1.3.3" 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)))

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.