pp 2.0.0 (latest) · OCaml Package

Pretty-printing.

type +'tag t

'tag t represents a document that is not yet rendered. The argument 'tag is the type of tags in the document. For instance tags might be used for styles.

If you want to serialise and deserialise this datastructure, you can use the Ast.t type together with the of_ast and to_ast functions.

Basic combinators

val nop : 'tag t

A pretty printer that prints nothing

val seq : 'tag t -> 'tag t -> 'tag t

seq x y prints x and then y

val concat : ?sep:'tag t -> 'tag t list -> 'tag t

concat ?sep l prints elements in l separated by sep. sep defaults to nop.

val concat_map : ?sep:'tag t -> 'a list -> f:('a -> 'tag t) -> 'tag t

Convenience function for List.map followed by concat.

val concat_mapi : ?sep:'tag t -> 'a list -> f:(int -> 'a -> 'tag t) -> 'tag t

Convenience function for List.mapi followed by concat.

val verbatim : string -> 'tag t

An indivisible block of text.

val verbatimf : ('a, unit, string, 'tag t) Stdlib.format4 -> 'a

Same as verbatim but take a format string as argument.

val char : char -> 'tag t

A single character.

val text : string -> 'tag t

Print a bunch of text. The line may be broken at any spaces in the text.

val textf : ('a, unit, string, 'tag t) Stdlib.format4 -> 'a

Same as text but take a format string as argument.

Break hints

val space : 'tag t

space instructs the pretty-printing algorithm that the line may be broken at this point. If the algorithm decides not to break the line, a single space will be printed instead.

So for instance verbatim "x" ++ space ++ verbatim "y" might produce "x y" or "x\n<indentation>y".

val cut : 'tag t

cut instructs the pretty-printing algorithm that the line may be broken at this point. If the algorithm decides not to break the line, nothing is printed instead.

So for instance verbatim "x" ++ space ++ verbatim "y" might produce "xy" or "x\n<indentation>y".

val break : nspaces:int -> shift:int -> 'tag t

break is a generalisation of space and cut. It also instructs the pretty-printing algorithm that the line may be broken at this point. If it ends up being broken, shift will be added to the indentation level, otherwise nspaces spaces will be printed. shift can be negative, in which case the indentation will be reduced.

val custom_break : 
  fits:(string * int * string) ->
  breaks:(string * int * string) ->
  'tag t

custom_break ~fits:(a, b, c) ~breaks:(x, y, z) is a generalisation of break. It also instructs the pretty-printing algorithm that the line may be broken at this point. If it ends up being broken, x is printed, the line breaks, y will be added to the indentation level and z is printed, otherwise a will be printed, b spaces are printed and then c is printed. The indentation y can be negative, in which case the indentation will be reduced.

val newline : 'tag t

Force a newline to be printed. Usage is discourage since it breaks printing with boxes. If you need to add breaks to your text, put your items into boxes and concat with a separating space afterwhich wrapping it in a vbox.

Boxes

Boxes are the basic components to control the layout of the text. Break hints such as space and cut may cause the line to be broken, depending on the splitting rules. Whenever a line is split, the rest of the material printed in the box is indented with indent.

You can think of a box with indentation as something with this shape:

       ######################### <- first line
       <indent>#################
       <indent>#################
       <indent>#################
       <indent>#################

And the top left corner of this shape is anchored where the box was declared. So for instance, the following document:

Pp.verbatim "....." ++ Pp.box ~indent:2 (Pp.text "some long ... text")

would produce:

       .....some long ...
              text

val box : ?indent:int -> 'tag t -> 'tag t

Try to put as much as possible on each line. Additionally, a break hint always break the line if the breaking would reduce the indentation level inside the box (break with negative shift value).

val vbox : ?indent:int -> 'tag t -> 'tag t

Always break the line when encountering a break hint.

val hbox : 'tag t -> 'tag t

Print everything on one line, no matter what

val hvbox : ?indent:int -> 'tag t -> 'tag t

If possible, print everything on one line. Otherwise, behave as a vbox

val hovbox : ?indent:int -> 'tag t -> 'tag t

Try to put as much as possible on each line. Basically the same as box but without the rule about breaks with negative shift value.

Convenience functions

val paragraph : string -> 'tag t

paragraph s is hovbox (text s). This is useful to preserve the structure of a paragraph of text without worrying about it being broken by a vbox.

val paragraphf : ('a, unit, string, 'tag t) Stdlib.format4 -> 'a

paragraphf s is textf s followed by a hovbox. The textf version of paragraph.

val enumerate : 'a list -> f:('a -> 'tag t) -> 'tag t

enumerate l ~f produces an enumeration of the form:

      - item1
      - item2
      - item3
      ...

val chain : 'a list -> f:('a -> 'tag t) -> 'tag t

chain l ~f is used to print a succession of items that follow each other. It produces an output of this form:

         item1
      -> item2
      -> item3
      ...

Operators

module O : sig ... end

Infix operators for Pp.t

Rendering

val to_fmt : Stdlib.Format.formatter -> 'tag t -> unit

Render a document to a classic formatter

val to_fmt_with_tags : 
  Stdlib.Format.formatter ->
  'tag t ->
  tag_handler:(Stdlib.Format.formatter -> 'tag -> 'tag t -> unit) ->
  unit

Ast

module Ast : sig ... end

Stable representation of Pp.t useful for serialization

val of_ast : 'tag Ast.t -> 'tag t

of_ast t converts an Ast.t to a Pp.t.

val to_ast : 'tag t -> 'tag Ast.t

to_ast t converts a Pp.t to an Ast.t.

Comparison

val compare : ('tag -> 'tag -> int) -> 'tag t -> 'tag t -> int

compare cmp x y compares x and y using cmp to compare tags.

package pp