package pprint

  1. Overview
  2. Docs

A set of high-level combinators for building documents.

Single characters

The following constant documents consist of a single character.

val lbracket : PPrintEngine.document
val rbracket : PPrintEngine.document
val backslash : PPrintEngine.document
val percent : PPrintEngine.document
val ampersand : PPrintEngine.document
val underscore : PPrintEngine.document

Delimiters

precede l x is l ^^ x.

terminate r x is x ^^ r.

The following combinators enclose a document within a pair of delimiters. They are partial applications of enclose. No whitespace or line break is introduced.

Repetition

twice doc is the document obtained by concatenating two copies of the document doc.

repeat n doc is the document obtained by concatenating n copies of the document doc.

Lists and options

concat docs is the concatenation of the documents in the list docs.

separate sep docs is the concatenation of the documents in the list docs. The separator sep is inserted between every two adjacent documents.

val concat_map : ('a -> PPrintEngine.document) -> 'a list -> PPrintEngine.document

concat_map f xs is equivalent to concat (List.map f xs).

val separate_map : PPrintEngine.document -> ('a -> PPrintEngine.document) -> 'a list -> PPrintEngine.document

separate_map sep f xs is equivalent to separate sep (List.map f xs).

separate2 sep last_sep docs is the concatenation of the documents in the list docs. The separator sep is inserted between every two adjacent documents, except between the last two documents, where the separator last_sep is used instead.

val optional : ('a -> PPrintEngine.document) -> 'a option -> PPrintEngine.document

optional f None is the empty document. optional f (Some x) is the document f x.

Text

val lines : string -> PPrintEngine.document list

lines s is the list of documents obtained by splitting s at newline characters, and turning each line into a document via substring. This code is not UTF-8 aware.

val arbitrary_string : string -> PPrintEngine.document

arbitrary_string s is equivalent to separate (break 1) (lines s). It is analogous to string s, but is valid even if the string s contains newline characters.

val words : string -> PPrintEngine.document list

words s is the list of documents obtained by splitting s at whitespace characters, and turning each word into a document via substring. All whitespace is discarded. This code is not UTF-8 aware.

val split : (char -> bool) -> string -> PPrintEngine.document list

split ok s splits the string s before and after every occurrence of a character that satisfies the predicate ok. The substrings thus obtained are turned into documents, and a list of documents is returned. No information is lost: the concatenation of the documents yields the original string. This code is not UTF-8 aware.

flow sep docs separates the documents in the list docs with the separator sep and arranges for a new line to begin whenever a document does not fit on the current line. This is useful for typesetting free-flowing, ragged-right text. A typical choice of sep is break b, where b is the number of spaces that must be inserted between two consecutive words (when displayed on the same line).

val flow_map : PPrintEngine.document -> ('a -> PPrintEngine.document) -> 'a list -> PPrintEngine.document

flow_map sep f docs is equivalent to flow sep (List.map f docs).

val url : string -> PPrintEngine.document

url s is a possible way of displaying the URL s. A potential line break is inserted immediately before and immediately after every slash and dot character.

Alignment and indentation

prefix n b left right has the following flat layout:

left right

and the following non-flat layout:

left
  right

The parameter n controls the nesting of right (when not flat). The parameter b controls the number of spaces between left and right (when flat).

val jump : int -> int -> PPrintEngine.document -> PPrintEngine.document

jump n b right is equivalent to prefix n b empty right.

infix n b middle left right has the following flat layout:

left middle right

and the following non-flat layout:

left middle
  right

The parameter n controls the nesting of right (when not flat). The parameter b controls the number of spaces between left and middle (always) and between middle and right (when flat).

surround n b opening contents closing has the following flat layout:

opening contents closing

and the following non-flat layout:

opening
  contents
closing

The parameter n controls the nesting of contents (when not flat). The parameter b controls the number of spaces between opening and contents and between contents and closing (when flat).

soft_surround is analogous to surround, but involves more than one group, so it offers possibilities other than the completely flat layout (where opening, contents, and closing appear on a single line) and the completely developed layout (where opening, contents, and closing appear on separate lines). It tries to place the beginning of contents on the same line as opening, and to place closing on the same line as the end of contents, if possible.

surround_separate n b void opening sep closing docs is equivalent to surround n b opening (separate sep docs) closing, except when the list docs is empty, in which case it reduces to void.

surround_separate_map n b void opening sep closing f xs is equivalent to surround_separate n b void opening sep closing (List.map f xs).

Short-hands

val (!^) : string -> PPrintEngine.document

!^s is a short-hand for string s.

x ^/^ y separates x and y with a breakable space. It is a short-hand for x ^^ break 1 ^^ y.

x ^//^ y is a short-hand for prefix 2 1 x y.

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