---
name: "Format_doc.Doc"
section: "3o"
platform: "linux"
package: "ocaml"
version: "5.5.0-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Format_doc.Doc"
---

# Format\_doc.Doc(3o)

Definitions and immutable API for composing documents

## NAME

Format\_doc.Doc - Definitions and immutable API for composing documents

## Module

Module   Format\_doc.Doc

## Documentation

Module **Doc**\
  :  **sig end**

Definitions and immutable API for composing documents

### Type definitions and core functions

*type box\_type* =\
  \| H\
  \| V\
  \| HV\
  \| HoV\
  \| B

Format box types

*type stag* =  **Format.stag**

*type element* =\
  \| Text **of** **string**\
  \| With\_size **of** **int**\
  \| Open\_box **of {**\
  kind :  **box\_type** ;\
  indent :  **int** ;\
  }\
  \| Close\_box\
  \| Open\_tag **of** **Format.stag**\
  \| Close\_tag\
  \| Open\_tbox\
  \| Tab\_break **of {**\
  width :  **int** ;\
  offset :  **int** ;\
  }\
  \| Set\_tab\
  \| Close\_tbox\
  \| Simple\_break **of {**\
  spaces :  **int** ;\
  indent :  **int** ;\
  }\
  \| Break **of {**\
  fits :  **string \* int \* string** ;\
  breaks :  **string \* int \* string** ;\
  }\
  \| Flush **of {**\
  newline :  **bool** ;\
  }\
  \| Newline\
  \| If\_newline\
  \| Deprecated **of** **(Format.formatter -\> unit)**   \
   (\* Escape hatch: a  **Format** printer used to provide backward-compatibility for user-defined printer (from the  **#install\_printer** toplevel directive for instance).\
  \*)

Base formatting instruction recognized by  **Format**

*type t*

Immutable document type

*type* **('a, 'b)** *fmt* =  **('a, t, t, 'b) format4**

*type printer0* =  **t -\> t**

*type* **'a** *printer* =  **'a -\> printer0**

*val empty* :  **t**

Empty document

*val format* :  **Format.formatter -\> t -\> unit**

**format ppf doc** sends the format instruction of  **doc** to the Format's formatter  **doc** .

*val fold* :  **('acc -\> element -\> 'acc) -\> 'acc -\> t -\> 'acc**

Fold over a document as a sequence of instructions

*val msg* :  **('a, t) fmt -\> 'a**

**Format\_doc.Doc.msg** and  **Format\_doc.Doc.kmsg** produce a document from a format string and its argument

*val kmsg* :  **(t -\> 'b) -\> ('a, 'b) fmt -\> 'a**

*val printf* :  **('a, printer0) fmt -\> 'a**

**Format\_doc.Doc.printf** and  **Format\_doc.Doc.kprintf** produce a printer from a format string and its argument

*val kprintf* :  **(t -\> 'b) -\>** **('a, t -\> 'b) fmt -\> 'a**

*val open\_box* :  **box\_type -\> int -\> printer0**

The functions below mirror  **Format** printers, without the  **pp\_print\_** prefix naming convention

*val close\_box* :  **printer0**

*val text* :  **string printer**

*val string* :  **string printer**

*val bytes* :  **bytes printer**

*val with\_size* :  **int printer**

*val int* :  **int printer**

*val float* :  **float printer**

*val char* :  **char printer**

*val bool* :  **bool printer**

*val space* :  **printer0**

*val cut* :  **printer0**

*val break* :  **spaces:int -\> indent:int -\> printer0**

*val custom\_break* :  **fits:string \* int \* string -\>** **breaks:string \* int \* string -\> printer0**

*val force\_newline* :  **printer0**

*val if\_newline* :  **printer0**

*val flush* :  **printer0**

*val force\_stop* :  **printer0**

*val open\_tbox* :  **printer0**

*val set\_tab* :  **printer0**

*val tab* :  **printer0**

*val tab\_break* :  **width:int -\> offset:int -\> printer0**

*val close\_tbox* :  **printer0**

*val open\_tag* :  **stag printer**

*val close\_tag* :  **printer0**

*val list* :  **?sep:printer0 -\>** **'a printer -\> 'a list printer**

*val iter* :  **?sep:printer0 -\>** **iter:(('a -\> unit) -\> 'b -\> unit) -\>** **'a printer -\> 'b printer**

*val array* :  **?sep:printer0 -\>** **'a printer -\> 'a array printer**

*val seq* :  **?sep:printer0 -\>** **'a printer -\> 'a Seq.t printer**

*val option* :  **?none:printer0 -\>** **'a printer -\> 'a option printer**

*val result* :  **ok:'a printer -\>** **error:'e printer -\>** **('a, 'e) result printer**

*val either* :  **left:'a printer -\>** **right:'b printer -\>** **('a, 'b) Either.t printer**

### Alignment functions

*val align\_prefix* :  **(t \* int) list -\> t list**

Align the right side of one  **"@{\<ralign\>...@}"** tag box by inserting spaces at the beginning of boxes. Those function do nothing if the tag box appears after a break hint.

*val align\_prefix2* :  **t \* int -\>** **t \* int -\> t \* t**