Text.PrettyPrint.MarkedHughesPJ

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.

Marking added by Andy Gill, Oct 08.

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

type Doc = MDoc ()

data MDoc a

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

Instances

Eq (MDoc a)

Show (MDoc a)

IsString (MDoc a)

Generic (MDoc a)

Monoid (MDoc a)

NFData a => NFData (MDoc a)

type Rep (MDoc a)

data TextDetails a

The TextDetails data type

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

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.

Mark a

Instances

Eq a => Eq (TextDetails a)

Show a => Show (TextDetails a)

Generic (TextDetails a)

NFData a => NFData (TextDetails a)

type Rep (TextDetails a)

Constructing documents

Converting values into documents

char :: Char -> MDoc a

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

text :: String -> MDoc a

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 -> MDoc a

Same as text. Used to be used for Bytestrings.

sizedText :: Int -> String -> MDoc a

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

zeroWidthText :: String -> MDoc a

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

int

Arguments

:: Int

-> MDoc a

int n = text (show n)

integer

Arguments

:: Integer

-> MDoc a

integer n = text (show n)

float

Arguments

:: Float

-> MDoc a

float n = text (show n)

double

Arguments

:: Double

-> MDoc a

double n = text (show n)

rational

Arguments

:: Rational

-> MDoc a

rational n = text (show n)

Simple derived documents

semi

Arguments

:: MDoc a

A ';' character

comma

Arguments

:: MDoc a

A ',' character

colon

Arguments

:: MDoc a

A : character

space

Arguments

:: MDoc a

A space character

equals

Arguments

:: MDoc a

A '=' character

lparen

Arguments

:: MDoc a

A '(' character

rparen

Arguments

:: MDoc a

A ')' character

lbrack

Arguments

:: MDoc a

A '[' character

rbrack

Arguments

:: MDoc a

A ']' character

lbrace

Arguments

:: MDoc a

A '{' character

rbrace

Arguments

:: MDoc a

A '}' character

Wrapping documents in delimiters

parens

Arguments

:: MDoc a

-> MDoc a

Wrap document in (...)

brackets

Arguments

:: MDoc a

-> MDoc a

Wrap document in [...]

braces

Arguments

:: MDoc a

-> MDoc a

Wrap document in {...}

quotes

Arguments

:: MDoc a

-> MDoc a

Wrap document in '...'

doubleQuotes

Arguments

:: MDoc a

-> MDoc a

Wrap document in "..."

maybeParens :: Bool -> MDoc a -> MDoc a

Apply parens to MDoc if boolean is true.

maybeBrackets :: Bool -> MDoc a -> MDoc a

Apply brackets to MDoc if boolean is true.

maybeBraces :: Bool -> MDoc a -> MDoc a

Apply braces to MDoc if boolean is true.

maybeQuotes :: Bool -> MDoc a -> MDoc a

Apply quotes to MDoc if boolean is true.

maybeDoubleQuotes :: Bool -> MDoc a -> MDoc a

Apply doubleQuotes to MDoc if boolean is true.

Combining documents

empty :: MDoc a

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.

(<>) :: MDoc a -> MDoc a -> MDoc a infixl 6

Beside. <> is associative, with identity empty.

(<+>) :: MDoc a -> MDoc a -> MDoc a infixl 6

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

hcat :: [MDoc a] -> MDoc a

List version of <>.

hsep :: [MDoc a] -> MDoc a

List version of <+>.

($$) :: MDoc a -> MDoc a -> MDoc a 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.

($+$) :: MDoc a -> MDoc a -> MDoc a infixl 5

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

vcat :: [MDoc a] -> MDoc a

List version of $$.

sep :: [MDoc a] -> MDoc a

Either hsep or vcat.

cat :: [MDoc a] -> MDoc a

Either hcat or vcat.

fsep :: [MDoc a] -> MDoc a

"Paragraph fill" version of sep.

fcat :: [MDoc a] -> MDoc a

"Paragraph fill" version of cat.

nest :: Int -> MDoc a -> MDoc a

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 :: MDoc a -> Int -> MDoc a -> MDoc a

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

punctuate :: MDoc a -> [MDoc a] -> [MDoc a]

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

Predicates on documents

isEmpty :: MDoc a -> Bool

Returns True if the document is empty

Utility functions for documents

first :: MDoc a -> MDoc a -> MDoc a

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

reduceDoc :: MDoc a -> RDoc a

Perform some simplification of a built up GDoc.

Rendering documents

Default rendering

render :: MDoc a -> String

Render the MDoc to a String using the default Style.

Rendering with a particular style

data Style

A rendering style.

Constructors

Style

Fields

mode :: Mode

The rendering mode

lineLength :: Int

Length of line, in chars

ribbonsPerLine :: Float

Ratio of line length to ribbon length

Instances

Eq Style

Show Style

Generic Style

type Rep Style

style :: Style

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

renderStyle :: Style -> MDoc a -> String

Render the MDoc to a String using the given Style.

data Mode

Rendering mode.

Constructors

PageMode

Normal

ZigZagMode

With zig-zag cuts

LeftMode

No indentation, infinitely long lines

OneLineMode

All on one line

Instances

Eq Mode

Show Mode

Generic Mode

type Rep Mode

General rendering

fullRender

Arguments

:: Mode

Rendering mode

-> Int

Line length

-> Float

Ribbons per line

-> (TextDetails b -> a -> a)

What to do with text

-> a

What to do at the end

-> MDoc b

The document

-> a

Result

The general rendering interface.

Markup extension

mark :: a -> MDoc a

mark inserts a zero width mark into the output document