BenchShow.Internal.Pretty

Documentation

data Doc

The abstract data type Doc represents pretty documents.

More specifically, a value of type Doc represents a non-empty set of possible renderings of a document. The rendering functions select one of these possibilities.

Doc is an instance of the Show class. (show doc) pretty prints document doc with a page width of 80 characters and a ribbon width of 32 characters.

show (text "hello" <$> text "world")

Which would return the string "hello\nworld", i.e.

hello
world

Instances

Show Doc

Defined in Text.PrettyPrint.ANSI.Leijen.Internal

Methods

showsPrec :: Int -> Doc -> ShowS

show :: Doc -> String

showList :: [Doc] -> ShowS

IsString Doc

Defined in Text.PrettyPrint.ANSI.Leijen.Internal

Methods

fromString :: String -> Doc

Semigroup Doc

Defined in Text.PrettyPrint.ANSI.Leijen.Internal

Methods

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

sconcat :: NonEmpty Doc -> Doc

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

Monoid Doc

Defined in Text.PrettyPrint.ANSI.Leijen.Internal

Methods

mempty :: Doc

mappend :: Doc -> Doc -> Doc

mconcat :: [Doc] -> Doc

Pretty Doc

Defined in Text.PrettyPrint.ANSI.Leijen.Internal

Methods

pretty :: Doc -> Doc

prettyList :: [Doc] -> Doc

dullred :: Doc -> Doc

Displays a document with the dull red forecolor

dullgreen :: Doc -> Doc

Displays a document with the dull green forecolor

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

The document (x <+> y) concatenates document x and y with a space in between. (infixr 6)

vcat :: [Doc] -> Doc

The document (vcat xs) concatenates all documents xs vertically with (<$$>). If a group undoes the line breaks inserted by vcat, all documents are directly concatenated.

fill :: Int -> Doc -> Doc

The document (fill i x) renders document x. It than appends spaces until the width is equal to i. If the width of x is already larger, nothing is appended. This combinator is quite useful in practice to output a list of bindings. The following example demonstrates this.

types  = [("empty","Doc")
         ,("nest","Int -> Doc -> Doc")
         ,("linebreak","Doc")]

ptype (name,tp)
       = fill 6 (text name) <+> text "::" <+> text tp

test   = text "let" <+> align (vcat (map ptype types))

Which is layed out as:

let empty  :: Doc
    nest   :: Int -> Doc -> Doc
    linebreak :: Doc

indent :: Int -> Doc -> Doc

The document (indent i x) indents document x with i spaces.

test  = indent 4 (fillSep (map text
        (words "the indent combinator indents these words !")))

Which lays out with a page width of 20 as:

    the indent
    combinator
    indents these
    words !

text :: String -> Doc

The document (text s) contains the literal string s. The string shouldn't contain any newline ('n') characters. If the string contains newline characters, the function string should be used.

putDoc :: Doc -> IO ()

The action (putDoc doc) pretty prints document doc to the standard output, with a page width of 80 characters and a ribbon width of 32 characters.

main :: IO ()
main = do{ putDoc (text "hello" <+> text "world") }

Which would output

hello world

Any ANSI colorisation in doc will be output.