darcs-2.12.5: a distributed, interactive, smart revision control system

Safe HaskellNone
LanguageHaskell2010

Darcs.Util.Printer

Contents

Description

A Document is at heart ShowS from the prelude

Essentially, if you give a Doc a string it'll print out whatever it wants followed by that string. So text "foo" makes the Doc that prints "foo" followed by its argument. The combinator names are taken from HughesPJ, although the behaviour of the two libraries is slightly different.

The advantage of Printer over simple string appending/concatenating is that the appends end up associating to the right, e.g.:

  (text "foo" <> text "bar") <> (text "baz" <> text "quux") ""
= \s -> (text "foo" <> text "bar") ((text "baz" <> text "quux") s) ""
= (text "foo" <> text "bar") ((text "baz" <> text "quux") "")
= (\s -> (text "foo") (text "bar" s)) ((text "baz" <> text "quux") "")
= text "foo" (text "bar" ((text "baz" <> text "quux") ""))
= (\s -> "foo" ++ s) (text "bar" ((text "baz" <> text "quux") ""))
= "foo" ++ (text "bar" ((text "baz" <> text "quux") ""))
= "foo" ++ ("bar" ++ ((text "baz" <> text "quux") ""))
= "foo" ++ ("bar" ++ ((\s -> text "baz" (text "quux" s)) ""))
= "foo" ++ ("bar" ++ (text "baz" (text "quux" "")))
= "foo" ++ ("bar" ++ ("baz" ++ (text "quux" "")))
= "foo" ++ ("bar" ++ ("baz" ++ ("quux" ++ "")))

The Empty alternative comes in because you want

text "a" $$ vcat xs $$ text "b"

$$ means above, vcat is the list version of $$ (to be "a\nb" when xs is []), but without the concept of an Empty Document each $$ would add a '\n' and you'd end up with "a\n\nb". Note that Empty /= text "" (the latter would cause two '\\n').

This code was made generic in the element type by Juliusz Chroboczek.

Synopsis

Doc type and structural combinators

newtype Doc #

A Doc is a bit of enriched text. Docs are concatenated using <> from class Monoid, which is right-associative.

Constructors

Doc 

Fields

  • unDoc :: St -> Document
     

Instances

IsString Doc #

Together with the language extension OverloadedStrings, this allows to use string literals where a Doc is expected.

Methods

fromString :: String -> Doc #

Monoid Doc #

mappend (<>) is concatenation, mempty is the empty Doc

Methods

mempty :: Doc #

mappend :: Doc -> Doc -> Doc #

mconcat :: [Doc] -> Doc #

empty :: Doc #

The empty Doc

(<>) :: Monoid m => m -> m -> m infixr 6 #

An infix synonym for mappend.

Since: 4.5.0.0

(<?>) :: Doc -> Doc -> Doc #

a <?> b is a <> b if a is not empty, else empty

(<+>) :: Doc -> Doc -> Doc infixr 6 #

a <+> b is a followed by a space, then b

($$) :: Doc -> Doc -> Doc infixr 5 #

a $$ b is a above b

vcat :: [Doc] -> Doc #

Pile Docs vertically

vsep :: [Doc] -> Doc #

Pile Docs vertically, with a blank line in between

hcat :: [Doc] -> Doc #

Concatenate Docs horizontally

hsep :: [Doc] -> Doc #

Concatenate Docs horizontally with a space as separator

minus :: Doc #

A Doc representing a "-"

newline :: Doc #

A Doc representing a newline

plus :: Doc #

A Doc representing a "+"

space :: Doc #

A Doc representing a space (" ")

backslash :: Doc #

A Doc representing a "\"

lparen :: Doc #

A Doc that represents "("

rparen :: Doc #

A Doc that represents ")"

parens :: Doc -> Doc #

parens d = lparen <> d <> rparen

Constructing Docs

text :: String -> Doc #

text creates a Doc from a String, using printable.

hiddenText :: String -> Doc #

hiddenText creates a Doc containing hidden text from a String

invisibleText :: String -> Doc #

invisibleText creates a Doc containing invisible text from a String

wrapText :: Int -> String -> Doc #

wrapText n s is a Doc representing s line-wrapped at n characters

quoted :: String -> Doc #

Quote a string for screen output

userchunk :: String -> Doc #

userchunk creates a Doc containing a user chunk from a String

prefix :: String -> Doc -> Doc #

invisiblePS :: ByteString -> Doc #

invisiblePS creates a Doc with invisible text from a ByteString

userchunkPS :: ByteString -> Doc #

userchunkPS creates a Doc representing a user chunk from a ByteString.

Rrrright. And what, please is that supposed to mean?

Rendering

data RenderMode #

Used when rendering a Doc to indicate if the result should be encoded to the current locale or left alone. In practice this only affects output when a relevant DARCS_DONT_ESCAPE_XXX option is set (see Darcs.Util.Printer.Color) If in doubt, choose Standard.

Constructors

Encode

Encode Strings with the current locale. At present ByteStrings are assumed to be in UTF8 and are left alone, so will be mis-encoded in non-UTF8 locales.

Standard

Don't encode.

renderString :: RenderMode -> Doc -> String #

renders a Doc into a String with control codes for the special features of the doc.

renderStringWith :: Printers' -> RenderMode -> Doc -> String #

renders a Doc into a String using a given set of printers.

renderPS :: RenderMode -> Doc -> ByteString #

renders a Doc into ByteString with control codes for the special features of the Doc. See also readerString.

renderPSWith :: Printers' -> RenderMode -> Doc -> ByteString #

renders a doc into a ByteString using a given set of printers.

renderPSs :: RenderMode -> Doc -> [ByteString] #

renders a Doc into a list of PackedStrings, one for each line.

renderPSsWith :: Printers' -> RenderMode -> Doc -> [ByteString] #

renders a Doc into a list of PackedStrings, one for each chunk of text that was added to the doc, using the given set of printers.

Printers

data Printers' #

A set of printers to print different types of text to a handle.

Constructors

Printers 

type Printer = Printable -> St -> Document #

simplePrinters :: Printers #

simplePrinters is a Printers which uses the set 'simplePriners\'' on any handle.

invisiblePrinter :: Printer #

invisiblePrinter is the Printer for hidden text. It just replaces the document with empty. It's useful to have a printer that doesn't actually do anything because this allows you to have tunable policies, for example, only printing some text if it's to the terminal, but not if it's to a file or vice-versa.

simplePrinter :: Printer #

simplePrinter is the simplest Printer: it just concatenates together the pieces of the Doc

Printables

data Printable #

A Printable is either a String, a packed string, or a chunk of text with both representations.

Constructors

S !String 
PS !ByteString 
Both !String !ByteString 

doc :: ([Printable] -> [Printable]) -> Doc #

printable :: Printable -> Doc #

Creates a Doc from any Printable.

invisiblePrintable :: Printable -> Doc #

Creates an invisible Doc from any Printable.

hiddenPrintable :: Printable -> Doc #

Creates a hidden Doc from any Printable.

userchunkPrintable :: Printable -> Doc #

Creates... WTF is a userchunk???

Constructing colored Docs

data Color #

Constructors

Blue 
Red 
Green 
Cyan 
Magenta 

colorText :: Color -> String -> Doc #

colorText creates a Doc containing colored text from a String

IO

hPutDoc :: RenderMode -> Handle -> Doc -> IO () #

hputDoc puts a doc on the given handle using simplePrinters

hPutDocLn :: RenderMode -> Handle -> Doc -> IO () #

hputDocLn puts a doc, followed by a newline on the given handle using simplePrinters.

putDoc :: Doc -> IO () #

putDoc puts a doc on stdout using the simple printer simplePrinters.

putDocLn :: Doc -> IO () #

putDocLn puts a doc, followed by a newline on stdout using simplePrinters

hPutDocWith :: Printers -> RenderMode -> Handle -> Doc -> IO () #

hputDocWith puts a doc on the given handle using the given printer.

hPutDocLnWith :: Printers -> RenderMode -> Handle -> Doc -> IO () #

hputDocLnWith puts a doc, followed by a newline on the given handle using the given printer.

putDocWith :: Printers -> Doc -> IO () #

putDocWith puts a doc on stdout using the given printer.

putDocLnWith :: Printers -> Doc -> IO () #

putDocLnWith puts a doc, followed by a newline on stdout using the given printer.

hPutDocCompr :: RenderMode -> Handle -> Doc -> IO () #

like hPutDoc but with compress data before writing

debugDocLn :: Doc -> IO () #

Write a Doc to stderr if debugging is turned on.

ePutDocLn :: Doc -> IO () #

eputDocLn puts a doc, followed by a newline to stderr using simplePrinters. Like putDocLn, it encodes with the user's locale. This function is the recommended way to output messages that should be visible to users on the console, but cannot (or should not) be silenced even when --quiet is in effect.

errorDoc :: Doc -> a #

Fail with a stack trace and the given Doc as error message.

Unsafe constructors

unsafeText :: String -> Doc #

unsafeText creates a Doc from a String, using simplePrinter directly

unsafeBoth :: String -> ByteString -> Doc #

unsafeBoth builds a Doc from a String and a ByteString representing the same text, but does not check that they do.

unsafeBothText :: String -> Doc #

unsafeBothText builds a Doc from a String. The string is stored in the Doc as both a String and a ByteString.

unsafeChar :: Char -> Doc #

unsafeChar creates a Doc containing just one character.