the-sett/elm-pretty-printer/2.1.3

NOTE: the latest version is 3.3.1

Pretty

Wadler's Pretty printer. Use the constructor functions to build up a Doc and lay it out to fit a page width using the pretty function.

type Doc

The type of documents that can be pretty printed.

Pretty printing documents

pretty : Int -> Doc -> String

Pretty prints a document trying to fit it as best as possible to the specified column width of the page.

Building documents from string data

Creates an empty document. Empties are discarded during pretty printing.

Note that the join, lines, softlines and words functions also filter out empties. So if a list of Docs are joined by spaces any that are empty will be dircarded and not result in a double space in the result. For this reason empty is not the same as string "".

pretty 10 empty == ""

Creates a document consisting of a single space.

string : String -> Doc

Creates a document from a string.

char : Char -> Doc

Creates a document from a character.

Joining documents together

append : Doc -> Doc -> Doc

Appends two documents together.

a : Doc -> Doc -> Doc

Short hand notation for append. Usefull when appending multiple parts together:

string "Hello"
    |> a space
    |> a "World"
    |> a (char '!')
    |> a line
join : Doc -> List Doc -> Doc

Concatenates a list of documents together interspersed with a separator document.

Any empty docs in the list are dropped, so that multiple separators will not be placed together with nothing in between them. If this behaviour is intended use string "" instead of empty.

lines : List Doc -> Doc

Concatenate a list of documents together interspersed with lines. Very convenient when laying out lines after another:

lines
  [ string "Heading"
  , empty
  , words [string "First", string "paragraph"]
  ...
  ]


==


string "Heading"
  |> a line
  |> a line
  |> a (string "First")
  |> a space
  |> a (string "paragraph")
  ...

Any empty docs in the list are dropped, so multiple lines will not be inserted around any empties.

See also words.

softlines : List Doc -> Doc

Like lines but uses softline instead.

Any empty docs in the list are dropped, so multiple lines will not be inserted around any empties.

words : List Doc -> Doc

Concatenate a list of documents together interspersed with spaces. Very convenient when laying out words after another.

See also lines.

Any empty docs in the list are dropped, so multiple spaces will not be inserted around any empties.

fold : (a -> Doc -> Doc) -> List a -> Doc

Fold a list of documents from left to right using a given function.

fold f == List.foldl f empty

Fitting documents onto lines

Tries to fit a document on a single line, replacing line breaks with single spaces where possible to achieve this.

Creates a hard line break. This always creates a new line, with subsequent text at the current indentation level.

Creates a line break that will render to a single space if the documents it separtes can be fitted onto one line, or a line break otherwise.

Indenting and alinging documents

Adds an indent of the current column position to all line breaks in the document. The first line will not be indented, only subsequent nested lines will be.

nest : Int -> Doc -> Doc

Adds an indent of the given number of spaces to all line breakss in the document. The first line will not be indented, only subsequent nested lines will be.

hang : Int -> Doc -> Doc

Adds an indent of the current column position to all line breaks in the document and a further indent of the specified number of columns. The first line will not be indented, only subsequent nested lines will be.

indent : Int -> Doc -> Doc

Indents a whole document by a given number of spaces.

Putting things around documents

surround : Doc -> Doc -> Doc -> Doc

Places a document inside left and right book ends.

pretty 100 (surround (char '\') (char '/') string "hello")
  == "\hello/"

Wraps a document in parnethesese

Wraps a document in braces.

Wraps a document in brackets.