Text.PrettyPrint.Leijen.Extended

This module is based, in part, on some of the interface for Text.PrettyPrint.Annotated.Leijen.

Pretty-print typeclass

class Pretty a where

Minimal complete definition

Nothing

Methods

pretty :: a -> StyleDoc

default pretty :: Show a => a -> StyleDoc

Instances

Pretty ModuleName

Defined in Text.PrettyPrint.Leijen.Extended

Methods

pretty :: ModuleName -> StyleDoc

Pretty PrettyException

Defined in RIO.PrettyPrint.PrettyException

Methods

pretty :: PrettyException -> StyleDoc

Pretty StyleDoc

Defined in Text.PrettyPrint.Leijen.Extended

Methods

pretty :: StyleDoc -> StyleDoc

Pretty (SomeBase Dir)

Defined in Text.PrettyPrint.Leijen.Extended

Methods

pretty :: SomeBase Dir -> StyleDoc

Pretty (SomeBase File)

Defined in Text.PrettyPrint.Leijen.Extended

Methods

pretty :: SomeBase File -> StyleDoc

Pretty (Path b Dir)

Defined in Text.PrettyPrint.Leijen.Extended

Methods

pretty :: Path b Dir -> StyleDoc

Pretty (Path b File)

Defined in Text.PrettyPrint.Leijen.Extended

Methods

pretty :: Path b File -> StyleDoc

Documents annotated by a style

newtype StyleDoc

A document annotated by a style.

Constructors

StyleDoc

Fields

• unStyleDoc :: Doc StyleAnn

Instances

IsString StyleDoc

Defined in Text.PrettyPrint.Leijen.Extended

Methods

fromString :: String -> StyleDoc

Monoid StyleDoc

Defined in Text.PrettyPrint.Leijen.Extended

Methods

mempty :: StyleDoc

mappend :: StyleDoc -> StyleDoc -> StyleDoc

mconcat :: [StyleDoc] -> StyleDoc

Semigroup StyleDoc

Defined in Text.PrettyPrint.Leijen.Extended

Methods

(<>) :: StyleDoc -> StyleDoc -> StyleDoc

sconcat :: NonEmpty StyleDoc -> StyleDoc

stimes :: Integral b => b -> StyleDoc -> StyleDoc

Show StyleDoc

Defined in Text.PrettyPrint.Leijen.Extended

Methods

showsPrec :: Int -> StyleDoc -> ShowS

show :: StyleDoc -> String

showList :: [StyleDoc] -> ShowS

Pretty StyleDoc

Defined in Text.PrettyPrint.Leijen.Extended

Methods

pretty :: StyleDoc -> StyleDoc

newtype StyleAnn

A style annotation.

Constructors

StyleAnn (Maybe Style)

Instances

Monoid StyleAnn

Defined in Text.PrettyPrint.Leijen.Extended

Methods

mempty :: StyleAnn

mappend :: StyleAnn -> StyleAnn -> StyleAnn

mconcat :: [StyleAnn] -> StyleAnn

Semigroup StyleAnn

Defined in Text.PrettyPrint.Leijen.Extended

Methods

(<>) :: StyleAnn -> StyleAnn -> StyleAnn

sconcat :: NonEmpty StyleAnn -> StyleAnn

stimes :: Integral b => b -> StyleAnn -> StyleAnn

Show StyleAnn

Defined in Text.PrettyPrint.Leijen.Extended

Methods

showsPrec :: Int -> StyleAnn -> ShowS

show :: StyleAnn -> String

showList :: [StyleAnn] -> ShowS

Eq StyleAnn

Defined in Text.PrettyPrint.Leijen.Extended

Methods

(==) :: StyleAnn -> StyleAnn -> Bool

(/=) :: StyleAnn -> StyleAnn -> Bool

displayAnsi :: (Pretty a, HasLogFunc env, HasStylesUpdate env, MonadReader env m, HasCallStack) => Int -> a -> m Utf8Builder

displayPlain :: (Pretty a, HasLogFunc env, HasStylesUpdate env, MonadReader env m, HasCallStack) => Int -> a -> m Utf8Builder

renderDefault :: Int -> Doc a -> SimpleDoc a

Selective use of the Text.PrettyPrint.Annotated.Leijen interface

Documented omissions by reference to package annotated-wl-pprint-0.7.0.

Documents, parametrized by their annotations

Omitted compared to original:

Doc, putDoc, hPutDoc

Basic combinators

Omitted compared to the original:

empty, char, text, (<>)

Instead of empty, use mempty.

Instead of char and text, use fromString.

A Monoid instance for StyleDoc is defined.

nest :: Int -> StyleDoc -> StyleDoc

The document (nest i x) renders document x with the current indentation level increased by i (See also hang, align and indent).

   nest 2 (fromString "hello" <> line <> fromString "world")
<> line
<> fromString "!"

outputs as:

hello
  world
!

line :: StyleDoc

The line document advances to the next line and indents to the current nesting level. Document line behaves like (fromString " ") if the line break is undone by group.

linebreak :: StyleDoc

The linebreak document advances to the next line and indents to the current nesting level. Document linebreak behaves like mempty if the line break is undone by group.

group :: StyleDoc -> StyleDoc

The group combinator is used to specify alternative layouts. The document (group x) undoes all line breaks in document x. The resulting line is added to the current line if that fits the page. Otherwise, the document x is rendered without any changes.

softline :: StyleDoc

The document softline behaves like (fromString " ") if the resulting output fits the page, otherwise it behaves like line.

softline = group line

softbreak :: StyleDoc

The document softbreak behaves like mempty if the resulting output fits the page, otherwise it behaves like line.

softbreak = group linebreak

Alignment

The combinators in this section can not be described by Wadler's original combinators. They align their output relative to the current output position - in contrast to nest which always aligns to the current nesting level. This deprives these combinators from being `optimal'. In practice however they prove to be very useful. The combinators in this section should be used with care, since they are more expensive than the other combinators. For example, align shouldn't be used to pretty print all top-level declarations of a language, but using hang for let expressions is fine.

Omitted compared to the original:

list, tupled, semiBraces

align :: StyleDoc -> StyleDoc

The document (align x) renders document x with the nesting level set to the current column. It is used for example to implement hang.

As an example, we will put a document right above another one, regardless of the current nesting level:

x $$ y = align (x <> line <> y)

test = fromString "hi" <+> (fromString "nice" $$ fromString "world")

which will be layed out as:

hi nice
   world

hang :: Int -> StyleDoc -> StyleDoc

The hang combinator implements hanging indentation. The document (hang i x) renders document x with a nesting level set to the current column plus i. The following example uses hanging indentation for some text:

test = hang 4 (fillSep (map fromString
       (words "the hang combinator indents these words !")))

Which lays out on a page with a width of 20 characters as:

the hang combinator
    indents these
    words !

The hang combinator is implemented as:

hang i x = align (nest i x)

indent :: Int -> StyleDoc -> StyleDoc

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

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

Which lays out with a page width of 20 as:

    the indent
    combinator
    indents these
    words !

encloseSep :: StyleDoc -> StyleDoc -> StyleDoc -> [StyleDoc] -> StyleDoc

The document (encloseSep l r sep xs) concatenates the documents xs separated by sep and encloses the resulting document by l and r. The documents are rendered horizontally if that fits the page. Otherwise they are aligned vertically. All separators are put in front of the elements. For example, the combinator list can be defined with encloseSep:

list xs = encloseSep lbracket rbracket comma xs
test = fromString "list" <+> (list (map int [10, 200, 3000]))

Which is layed out with a page width of 20 as:

list [10,200,3000]

But when the page width is 15, it is layed out as:

list [10
     ,200
     ,3000]

Operators

Omitted compared to the original:

(<$>), (</>), (<$$>), (<//>)

(<+>) :: StyleDoc -> StyleDoc -> StyleDoc

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

List combinators

hsep :: [StyleDoc] -> StyleDoc

The document (hsep xs) concatenates all documents xs horizontally with (<+>).

vsep :: [StyleDoc] -> StyleDoc

The document (vsep xs) concatenates all documents xs vertically with (<> line <>). If a group undoes the line breaks inserted by vsep, all documents are separated with a space.

someText = map fromString (words ("text to lay out"))

test = fromString "some" <+> vsep someText

This is layed out as:

some text
to
lay
out

The align combinator can be used to align the documents under their first element

test = fromString "some" <+> align (vsep someText)

Which is printed as:

some text
     to
     lay
     out

fillSep :: [StyleDoc] -> StyleDoc

The document (fillSep xs) concatenates documents xs horizontally with (<+>) as long as its fits the page, than inserts a line and continues doing that for all documents in xs.

fillSep xs = foldr (<> softline <>) mempty xs

sep :: [StyleDoc] -> StyleDoc

The document (sep xs) concatenates all documents xs either horizontally with (<+>), if it fits the page, or vertically with (<> line <>).

sep xs = group (vsep xs)

hcat :: [StyleDoc] -> StyleDoc

The document (hcat xs) concatenates all documents xs horizontally with (<>).

vcat :: [StyleDoc] -> StyleDoc

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

fillCat :: [StyleDoc] -> StyleDoc

The document (fillCat xs) concatenates documents xs horizontally with (<>) as long as its fits the page, than inserts a linebreak and continues doing that for all documents in xs.

fillCat xs = foldr (<> softbreak <>) mempty xs

cat :: [StyleDoc] -> StyleDoc

The document (cat xs) concatenates all documents xs either horizontally with (<>), if it fits the page, or vertically with (<> linebreak <>).

cat xs = group (vcat xs)

punctuate :: StyleDoc -> [StyleDoc] -> [StyleDoc]

(punctuate p xs) concatenates all documents in xs with document p except for the last document.

someText = map fromString ["words", "in", "a", "tuple"]
test = parens (align (cat (punctuate comma someText)))

This is layed out on a page width of 20 as:

(words,in,a,tuple)

But when the page width is 15, it is layed out as:

(words,
 in,
 a,
 tuple)

(If you want put the commas in front of their elements instead of at the end, you should use encloseSep.)

Fillers

fill :: Int -> StyleDoc -> StyleDoc

The document (fill i x) renders document x. It than appends (fromString " ")s 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 a")
        , ("nest", "Int -> Doc a -> Doc a")
        , ("linebreak", "Doc a")
        ]

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

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

Which is layed out as:

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

fillBreak :: Int -> StyleDoc -> StyleDoc

The document (fillBreak i x) first renders document x. It then appends (fromString " ")s until the width is equal to i. If the width of x is already larger than i, the nesting level is increased by i and a line is appended. When we redefine ptype in the previous example to use fillBreak, we get a useful variation of the previous output:

ptype (name, tp) =
  fillBreak 6 (fromString name) <+> fromString "::" <+> fromString tp

The output will now be:

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

Bracketing combinators

enclose :: StyleDoc -> StyleDoc -> StyleDoc -> StyleDoc

The document (enclose l r x) encloses document x between documents l and r using (<>).

enclose l r x   = l <> x <> r

squotes :: StyleDoc -> StyleDoc

Document (squotes x) encloses document x with single quotes "'".

dquotes :: StyleDoc -> StyleDoc

Document (dquotes x) encloses document x with double quotes '"'.

parens :: StyleDoc -> StyleDoc

Document (parens x) encloses document x in parenthesis, "(" and ")".

angles :: StyleDoc -> StyleDoc

Document (angles x) encloses document x in angles, "<" and ">".

braces :: StyleDoc -> StyleDoc

Document (braces x) encloses document x in braces, "{" and "}".

brackets :: StyleDoc -> StyleDoc

Document (brackets x) encloses document x in square brackets, "[" and "]".

Character documents

Entirely omitted:

lparen, rparen, langle, rangle, lbrace, rbrace, lbracket, rbracket,
squote, dquote, semi, colon, comma, space, dot, backslash, equals,
pipe

Primitive type documents

Omitted compared to the original:

int, integer, float, double, rational, bool

string :: String -> StyleDoc

The document string s concatenates all characters in s using line for newline characters and fromString for all other characters. It is used whenever the text contains newline characters.

Since: 0.1.4.0

Semantic annotations

annotate :: StyleAnn -> StyleDoc -> StyleDoc

noAnnotate :: StyleDoc -> StyleDoc

Strip annotations from a document. This is useful for re-using the textual formatting of some sub-document, but applying a different high-level annotation.

styleAnn :: Style -> StyleDoc -> StyleDoc

Rendering

Entirely omitted:

SimpleDoc (..), renderPretty, renderCompact, displayDecorated,
displayDecoratedA, display, displayS, displayIO, SpanList (..),
displaySpans

Undocumented

Entirely omitted:

column, nesting, width