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 |
John Hughes's and Simon Peyton Jones's Pretty Printer Combinators
Based on The Design of a Pretty-printing Library in Advanced Functional Programming, Johan Jeuring and Erik Meijer (eds), LNCS 925 http://www.cs.chalmers.se/~rjmh/Papers/pretty.ps
- data Doc
- data TextDetails
- char :: Char -> Doc
- text :: String -> Doc
- ptext :: String -> Doc
- sizedText :: Int -> String -> Doc
- zeroWidthText :: String -> Doc
- int :: Int -> Doc
- integer :: Integer -> Doc
- float :: Float -> Doc
- double :: Double -> Doc
- rational :: Rational -> Doc
- semi :: Doc
- comma :: Doc
- colon :: Doc
- space :: Doc
- equals :: Doc
- lparen :: Doc
- rparen :: Doc
- lbrack :: Doc
- rbrack :: Doc
- lbrace :: Doc
- rbrace :: Doc
- parens :: Doc -> Doc
- brackets :: Doc -> Doc
- braces :: Doc -> Doc
- quotes :: Doc -> Doc
- doubleQuotes :: Doc -> Doc
- maybeParens :: Bool -> Doc -> Doc
- maybeBrackets :: Bool -> Doc -> Doc
- maybeBraces :: Bool -> Doc -> Doc
- maybeQuotes :: Bool -> Doc -> Doc
- maybeDoubleQuotes :: Bool -> Doc -> Doc
- empty :: Doc
- (<>) :: Doc -> Doc -> Doc
- (<+>) :: Doc -> Doc -> Doc
- hcat :: [Doc] -> Doc
- hsep :: [Doc] -> Doc
- ($$) :: Doc -> Doc -> Doc
- ($+$) :: Doc -> Doc -> Doc
- vcat :: [Doc] -> Doc
- sep :: [Doc] -> Doc
- cat :: [Doc] -> Doc
- fsep :: [Doc] -> Doc
- fcat :: [Doc] -> Doc
- nest :: Int -> Doc -> Doc
- hang :: Doc -> Int -> Doc -> Doc
- punctuate :: Doc -> [Doc] -> [Doc]
- isEmpty :: Doc -> Bool
- first :: Doc -> Doc -> Doc
- reduceDoc :: Doc -> RDoc
- render :: Doc -> String
- data Style = Style {
- mode :: Mode
- lineLength :: Int
- ribbonsPerLine :: Float
- style :: Style
- renderStyle :: Style -> Doc -> String
- data Mode
- fullRender :: Mode -> Int -> Float -> (TextDetails -> a -> a) -> a -> Doc -> a
The document type
The abstract type of documents. A Doc represents a *set* of layouts. A Doc with no occurrences of Union or NoDoc represents just one layout.
data TextDetails Source
The TextDetails data type
A TextDetails represents a fragment of text that will be output at some point.
Constructing documents
Converting values into documents
zeroWidthText :: String -> Doc Source
Some text, but without any width. Use for non-printing text such as a HTML or Latex tags
Simple derived documents
Wrapping documents in delimiters
maybeDoubleQuotes :: Bool -> Doc -> Doc Source
Apply doubleQuotes
to Doc
if boolean is true.
Combining documents
($$) :: 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" $$ nest 5 (text "there")
lays out as
hi there
rather than
hi there
nest :: Int -> Doc -> Doc Source
Nest (or indent) a document by a given number of positions
(which may also be negative). nest
satisfies the laws:
nest
0 x = xnest
k (nest
k' x) =nest
(k+k') xnest
k (x<>
y) =nest
k z<>
nest
k ynest
k (x$$
y) =nest
k x$$
nest
k ynest
kempty
=empty
x
, if<>
nest
k y = x<>
yx
non-empty
The side condition on the last law is needed because
empty
is a left identity for <>
.
punctuate :: Doc -> [Doc] -> [Doc] Source
punctuate p [d1, ... dn] = [d1 <> p, d2 <> p, ... dn-1 <> p, dn]
Predicates on documents
Utility functions for documents
first :: Doc -> Doc -> Doc Source
first
returns its first argument if it is non-empty, otherwise its second.
Rendering documents
Default rendering
Rendering with a particular style
A rendering style.
Style | |
|
renderStyle :: Style -> Doc -> String Source
Render the Doc
to a String using the given Style
.
Rendering mode.
PageMode | Normal |
ZigZagMode | With zig-zag cuts |
LeftMode | No indentation, infinitely long lines |
OneLineMode | All on one line |
General rendering
:: 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.