OCAML DOCUMENTATION

Prerequisites

• Any prerequisites required to build the OCaml compiler from sources.

• A LaTeX installation.

• The HeVeA LaTeX-to-HTML converter (available in OPAM): http://hevea.inria.fr/

Note that you must make sure hevea.sty is installed into TeX properly. Your package manager may not do this for you. Run kpsewhich hevea.sty to check.

Building the manual

0. Build the OCaml compiler (including the native one) from sources.

You don't need to install the compiler since the manual is built using the one from the source tree.

1. Run make in the manual directory.

Outputs

In the manual:

• The HTML Manual is in directory htmlman. The main file is index.html.

• The plain text manual is in directory textman as file manual.txt.

• The Info manual is in directory infoman.

• The PDF manual is in directory texstuff as file manual.pdf.

Source files

The manual is written in an extended dialect of LaTeX and is split across many source files. During the build process, these source files are converted into classical LaTeX files using the tools available in the manual/tools directory. These files are then converted to the different output formats using either LaTeX or hevea.

Each part of the manual corresponds to a specific directory, and each distinct chapters (or sometimes sections) are mapped to a distinct .etex file:

• Part I, Introduction to OCaml: tutorials

  • The core language: coreexamples.etex
  • The module system: moduleexamples.etex
  • Objects in OCaml: objectexamples.etex
  • Labels and variants: lablexamples.etex
  • Advanced examples with classes and modules: advexamples.etex

• Part II, The OCaml language: refman This part is divided in two very distinct chapters; the OCaml language chapter and the Language extensions chapter.

  • The OCaml language: refman.etex This chapter consists in a technical description of the OCaml language. Each section of this chapter is mapped to a separate LaTeX file:

    • lex.etex, values.etex, names.etex, types.etex, const.etex, patterns.etex, expr.etex, typedecl.etex, classes.etex, modtypes.etex, compunit.etex

  • Language extensions: exten.etex This chapter contains a description of all recent features of the OCaml language.

• Part III, The OCaml tools: 'cmds'

  • Batch compilation (ocamlc): comp.etex
  • The toplevel system (ocaml): top.etex
  • The runtime system (ocamlrun): runtime.etex
  • Native-code compilation (ocamlopt): native.etex
  • Lexer and parser generators (ocamllex, ocamlyacc): lexyacc.etex
  • Dependency generator (ocamldep): ocamldep.etex
  • The documentation generator (ocamldoc): ocamldoc.etex
  • The debugger (ocamldebug): debugger.etex
  • Profiling (ocamlprof, perf): profil.etex
  • Interfacing C with OCaml: intf-c.etex
  • Optimisation with Flambda: flambda.etex
  • Fuzzing with afl-fuzz: afl-fuzz.etex
  • Runtime tracing with Runtime_events: runtime_tracing.etex
  • The “Tail Modulo Constructor” program transformation: tail-mod-cons.etex
  • Runtime detection of data races with ThreadSanitizer: tsan.etex

Note that ocamlc,ocamlopt and the toplevel options overlap a lot. Consequently, these options are described together in the file unified-options.etex and then included from comp.etex, native.etex, and top.etex. If you need to update this list of options, the top comment of unified-options.etex contains the relevant information.

• Part IV, The OCaml library: 'library' This parts contains an brief presentation of all libraries bundled with the compilers and the api documentation generated for these libraries.
  • The core library: core.etex
  • The standard library: stdlib-blurb.etex
  • The compiler front-end: compilerlibs.etex
  • The unix library: Unix system calls: libunix.etex
  • The str library: regular expressions and string processing: libstr.etex
  • The threads library: libthreads.etex
  • The runtime_events library: libruntime_events.etex
  • The dynlink library: dynamic loading and linking of object files: libdynlink.etex
  • Recently removed or moved libraries (Graphics, Bigarray, Num, LablTk): old.etex

Latex extensions

Sections (and subsections, and subsubsections)

In order to provide stable links to all part of the manual, the standard \section, \subsection and \subsubsection macros are replaced by variants that take the section label as their first argument. For instance, in the manual, you have to write

\section{s:basics}{Basics}

rather than

\section{Basics\label{s:basics}}

This restriction ensures that hevea picks the section label when generating the header ids.

A similar macro, \lparagraph, is provided for paragraphs.

Caml environments

The tool tools/ocamltex is used to generate the LaTeX code for the examples in the introduction and language extension parts of the manual. It implements two pseudo-environments: caml_example and caml_eval.

The pseudo-environment caml_example evaluates its contents using an ocaml interpreter and then translates both the input code and the interpreter output to LaTeX code, e.g.

\begin{caml_example}{toplevel}
let f x = x;;
\end{caml_example}

Note that the toplevel output can be suppressed by using a * suffix:

\begin{caml_example*}{verbatim}
let f x = x
\end{caml_example*}

The {verbatim} or {toplevel} argument of the environment corresponds to the mode of the example. Three modes are available -- toplevel, verbatim and signature. The toplevel mode mimics the appearance and behavior of the toplevel. In particular, toplevel examples must end with a double semi-colon ;;, otherwise an error would be raised. The verbatim does not require a final ;; and is intended to be a lighter mode for code examples. If you want to declare a signature instead of ocaml code, you must use the {signature} argument to the caml_example environment.

\begin{caml_example*}{signature}
val none : 'a option
\end{caml_example*}

By default, ocamltex raises an error and stops if the output of one the caml_example environment contains an unexpected error or warning. If such an error or warning is, in fact, expected, it is necessary to indicate the expected output status to ocamltex by adding either an option to the caml_example environment:

\begin{caml_example}{toplevel}[error]
1 + 2. ;;
\end{caml_example}
 or for warning
\begin{caml_example}[warning=8]
let f None = None;;
\end{caml_example}

or an annotation to the concerned phrase:

\begin{caml_example}{toplevel}
1 + 2. [@@expect error] ;;
let f None = None [@@expect warning 8];;
3 + 4 [@@expect ok];;
\end{caml_example}

It is also possible to elide a code fragment by annotating it with an [@ellipsis] attribute

\begin{caml_example}{toplevel}
let f: type a. a list -> int = List.length[@ellipsis] ;;
\end{caml_example}

For module components, it might be easier to hide them by using [@@@ellipsis.start] and [@@@ellipsis.stop]:

\begin{caml_example*}{verbatim}
module M = struct
  [@@@ellipsis.start]
  type t = T
  let x = 0
  [@@@ellipsis.stop]
 end
\end{caml_example*}

Another possibility to avoid displaying distracting code is to use the caml_eval environment. This environment is a companion environment to caml_example and can be used to evaluate OCaml expressions in the toplevel without printing anything:

\begin{caml_eval}
let pi = 4. *. atan 1.;;
\end{caml_eval}
\begin{caml_example}{toplevel}
let f x = x +. pi;;
\end{caml_example}

Beware that the detection code for these pseudo-environments is quite brittle and the environments must start and end at the beginning of the line.

Quoting

The tool tools/texquote2 provides support for verbatim-like quotes using \" delimiters. More precisely, outside of caml environments and verbatim environments, texquote2 translates double quotes "text" to \machine{escaped_text}.

BNF grammar notation

The tool tools/transf provides support for BNF grammar notations and special quotes for non-terminal. When transf is used, the environment syntax can be used to describe grammars using BNF notation:

\begin{syntax}
expr:
    value-path
  | constant
  | '(' expr ')'
  | 'begin' expr 'end'
  | '(' expr ':' typexpr ')'
  | expr {{',' expr}}
  | constr expr
  | "`"tag-name expr
  | expr '::' expr
  | '[' expr { ';' expr } [';'] ']'
  | '[|' expr { ';' expr } [';'] '|]'
  | '{' field [':' typexpr] '=' expr%
    { ';' field [':' typexpr] '=' expr } [';'] '}'
\end{syntax}

Notice that terminal symbols are quoted using ' delimiters. Moreover, outside of the syntax environment, @-quotes can be used to introduce fragment of grammar: @'(' module-expr ')'@. As a consequence, when this extension is used @ characters must be escaped as \@. This extension is used mainly in the language reference part of the manual. and a more complete description of the notation used is available in the first subsection of refman/refman.etex.

Consistency tests

The tests folder contains consistency tests that checks that the manual and the rest of the compiler sources stay synced.