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<H1>OCAML</H1>
Section: User Commands (1)<BR><A HREF="#index">Index</A>
<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
<P>
<A NAME="lbAB">&nbsp;</A>
<H2>NAME</H2>
ocaml - The OCaml interactive toplevel
<P>
<A NAME="lbAC">&nbsp;</A>
<H2>SYNOPSIS</H2>
<B>ocaml</B>
[
<I>options</I>
]
[
<I>object-files</I>
]
[
<I>script-file</I>
]
<A NAME="lbAD">&nbsp;</A>
<H2>DESCRIPTION</H2>
<P>
The
<B><A HREF="/cgi-bin/man/man2html?1+ocaml">ocaml</A></B>(1)
command is the toplevel system for OCaml,
that permits interactive use of the OCaml system through a
read-eval-print loop. In this mode, the system repeatedly reads OCaml
phrases from the input, then typechecks, compiles and evaluates
them, then prints the inferred type and result value, if any. The
system prints a # (hash) prompt before reading each phrase.
<P>
A toplevel phrase can span several lines. It is terminated by ;; (a
double-semicolon). The syntax of toplevel phrases is as follows.
<P>
The toplevel system is started by the command
<B><A HREF="/cgi-bin/man/man2html?1+ocaml">ocaml</A></B>(1).
Phrases are read on standard input, results are printed on standard
output, errors on standard error. End-of-file on standard input
terminates
<B><A HREF="/cgi-bin/man/man2html?1+ocaml">ocaml</A></B>(1).
<P>
If one or more
<I>object-files</I>
(ending in .cmo or .cma) are given, they are loaded silently before
starting the toplevel.
<P>
If a
<I>script-file</I>
is given, phrases are read silently from the file, errors printed on
standard error.
<B><A HREF="/cgi-bin/man/man2html?1+ocaml">ocaml</A></B>(1)
exits after the execution of the last phrase.
<P>
<A NAME="lbAE">&nbsp;</A>
<H2>OPTIONS</H2>
<P>
The following command-line options are recognized by
<B><A HREF="/cgi-bin/man/man2html?1+ocaml">ocaml</A></B>(1).
<DL COMPACT>
<DT id="1"><B>-absname</B>
<DD>
Show absolute filenames in error messages.
<DT id="2"><B>-I</B><I>&nbsp;directory</I>
<DD>
Add the given directory to the list of directories searched for
source and compiled files. By default, the current directory is
searched first, then the standard library directory. Directories added
with
<B>-I</B>
are searched after the current directory, in the order in which they
were given on the command line, but before the standard library
directory.
<DT id="3"><DD>
If the given directory starts with
<B>+</B>,
it is taken relative to the
standard library directory. For instance,
<B>-I&nbsp;+compiler-libs</B>
adds the subdirectory
<B>compiler-libs</B>
of the standard library to the search path.
<DT id="4"><DD>
Directories can also be added to the search path once the toplevel
is running with the
<B>#directory</B>
directive.
<DT id="5"><B>-init</B><I>&nbsp;file</I>
<DD>
Load the given file instead of the default initialization file.
See the &quot;Initialization file&quot; section below.
<DT id="6"><B>-labels</B>
<DD>
Labels are not ignored in types, labels may be used in applications,
and labelled parameters can be given in any order. This is the default.
<DT id="7"><B>-no-app-funct</B>
<DD>
Deactivates the applicative behaviour of functors. With this option,
each functor application generates new types in its result and
applying the same functor twice to the same argument yields two
incompatible structures.
<DT id="8"><B>-noassert</B>
<DD>
Do not compile assertion checks. Note that the special form
<B>assert&nbsp;false</B>
is always compiled because it is typed specially.
<DT id="9"><B>-noinit</B>
<DD>
Do not load any initialization file.
See the &quot;Initialization file&quot; section below.
<DT id="10"><B>-nolabels</B>
<DD>
Ignore non-optional labels in types. Labels cannot be used in
applications, and parameter order becomes strict.
<DT id="11"><B>-noprompt</B>
<DD>
Do not display any prompt when waiting for input.
<DT id="12"><B>-nopromptcont</B>
<DD>
Do not display the secondary prompt when waiting for continuation lines in
multi-line inputs. This should be used e.g. when running
<B><A HREF="/cgi-bin/man/man2html?1+ocaml">ocaml</A></B>(1)
in an
<B><A HREF="/cgi-bin/man/man2html?1+emacs">emacs</A></B>(1)
window.
<DT id="13"><B>-nostdlib</B>
<DD>
Do not include the standard library directory in the list of
directories searched for source and compiled files.
<DT id="14"><B>-open</B><I>&nbsp;module</I>
<DD>
Opens the given module before starting the toplevel. If several
<B>-open</B>
options are given, they are processed in order, just as if
the statements open! module1;; ... open! moduleN;; were input.
<DT id="15"><B>-ppx</B><I>&nbsp;command</I>
<DD>
After parsing, pipe the abstract syntax tree through the preprocessor
<I>command</I>.
The module
<B><A HREF="/cgi-bin/man/man2html?3+Ast_mapper">Ast_mapper</A></B>(3)
implements the external interface of a preprocessor.
<DT id="16"><B>-principal</B>
<DD>
Check information path during type-checking, to make sure that all
types are derived in a principal way. When using labelled arguments
and/or polymorphic methods, this flag is required to ensure future
versions of the compiler will be able to infer types correctly, even
if internal algorithms change.
All programs accepted in
<B>-principal</B>
mode are also accepted in the
default mode with equivalent types, but different binary signatures,
and this may slow down type checking; yet it is a good idea to
use it once before publishing source code.
<DT id="17"><B>-rectypes</B>
<DD>
Allow arbitrary recursive types during type-checking. By default,
only recursive types where the recursion goes through an object type
are supported.
<DT id="18"><B>-safe-string</B>
<DD>
Enforce the separation between types
<B>string</B>&nbsp;and&nbsp;<B>bytes</B>,
thereby making strings read-only. This is the default.
<DT id="19"><B>-short-paths</B>
<DD>
When a type is visible under several module-paths, use the shortest
one when printing the type's name in inferred interfaces and error and
warning messages.
<DT id="20"><B>-stdin</B>
<DD>
Read the standard input as a script file rather than starting an
interactive session.
<DT id="21"><B>-strict-sequence</B>
<DD>
Force the left-hand part of each sequence to have type unit.
<DT id="22"><B>-unboxed-types</B>
<DD>
When a type is unboxable (i.e. a record with a single argument or a
concrete datatype with a single constructor of one argument) it will
be unboxed unless annotated with
<B>[@@ocaml.boxed]</B>.
<DT id="23"><B>-no-unboxed-types</B>
<DD>
When a type is unboxable it will be boxed unless annotated with
<B>[@@ocaml.unboxed]</B>.
This is the default.
<DT id="24"><B>-unsafe</B>
<DD>
Turn bound checking off on array and string accesses (the
<B>v.(i)</B>and<B>s.[i]</B>
constructs). Programs compiled with
<B>-unsafe</B>
are therefore slightly faster, but unsafe: anything can happen if the program
accesses an array or string outside of its bounds.
<DT id="25"><B>-unsafe-string</B>
<DD>
Identify the types
<B>string</B>&nbsp;and&nbsp;<B>bytes</B>,
thereby making strings writable.
This is intended for compatibility with old source code and should not
be used with new software.
<DT id="26"><B>-version</B>
<DD>
Print version string and exit.
<DT id="27"><B>-vnum</B>
<DD>
Print short version number and exit.
<DT id="28"><B>-no-version</B>
<DD>
Do not print the version banner at startup.
<DT id="29"><B>-w</B><I>&nbsp;warning-list</I>
<DD>
Enable or disable warnings according to the argument
<I>warning-list</I>.
See
<B><A HREF="/cgi-bin/man/man2html?1+ocamlc">ocamlc</A></B>(1)
for the syntax of the
<I>warning-list</I>
argument.
<DT id="30"><B>-warn-error</B><I>&nbsp;warning-list</I>
<DD>
Mark as fatal the warnings described by the argument
<I>warning-list</I>.
Note that a warning is not triggered (and does not trigger an error) if
it is disabled by the
<B>-w</B>
option. See
<B><A HREF="/cgi-bin/man/man2html?1+ocamlc">ocamlc</A></B>(1)
for the syntax of the
<I>warning-list</I>
argument.
<DT id="31"><B>-color</B><I>&nbsp;mode</I>
<DD>
Enable or disable colors in compiler messages (especially warnings and errors).
The following modes are supported:
<P>
<B>auto</B>
use heuristics to enable colors only if the output supports them (an
ANSI-compatible tty terminal);
<P>
<B>always</B>
enable colors unconditionally;
<P>
<B>never</B>
disable color output.
<P>
The default setting is
<B>auto,</B>
and the current heuristic
checks that the &quot;TERM&quot; environment variable exists and is
not empty or &quot;dumb&quot;, and that isatty(stderr) holds.
<P>
The environment variable &quot;OCAML_COLOR&quot; is considered if -color is not
provided. Its values are auto/always/never as above.
<P>
<DT id="32"><B>-error-style</B><I>&nbsp;mode</I>
<DD>
Control the way error messages and warnings are printed.
The following modes are supported:
<P>
<B>short</B>
only print the error and its location;
<P>
<B>contextual</B>
like &quot;short&quot;, but also display the source code snippet corresponding
to the location of the error.
<P>
The default setting is
<B>contextual.</B>
<P>
The environment variable &quot;OCAML_ERROR_STYLE&quot; is considered if
-error-style is not provided. Its values are short/contextual as
above.
<P>
<DT id="33"><B>-warn-help</B>
<DD>
Show the description of all available warning numbers.
<DT id="34"><B>-</B><I>&nbsp;file</I>
<DD>
Use
<I>file</I>
as a script file name, even when it starts with a hyphen (-).
<DT id="35"><B>-help</B>&nbsp;or<B>&nbsp;--help</B>
<DD>
Display a short usage summary and exit.
<P>
</DL>
<A NAME="lbAF">&nbsp;</A>
<H2>INITIALIZATION FILE</H2>
<P>
When
<B><A HREF="/cgi-bin/man/man2html?1+ocaml">ocaml</A></B>(1)
is invoked, it will read phrases from an initialization file before
giving control to the user. The default file is
<B>.ocamlinit</B>
in the current directory if it exists, otherwise
<B>.ocamlinit</B>
in the user's home directory. You can specify a different initialization file
by using the
<B>-init</B><I>&nbsp;file</I>
option, and disable initialization files by using the
<B>-noinit</B>
option.
<P>
Note that you can also use the
<B>#use</B>
directive to read phrases from a file.
<P>
<A NAME="lbAG">&nbsp;</A>
<H2>ENVIRONMENT VARIABLES</H2>
<DL COMPACT>
<DT id="36"><B>OCAMLTOP_UTF_8</B>
<DD>
When printing string values, non-ascii bytes (&gt;0x7E) are printed as
decimal escape sequence if
<B>OCAMLTOP_UTF_8</B>
is set to false. Otherwise they are printed unescaped.
<DT id="37"><B>TERM</B>
<DD>
When printing error messages, the toplevel system
attempts to underline visually the location of the error. It
consults the TERM variable to determines the type of output terminal
and look up its capabilities in the terminal database.
<P>
</DL>
<A NAME="lbAH">&nbsp;</A>
<H2>SEE ALSO</H2>
<B><A HREF="/cgi-bin/man/man2html?1+ocamlc">ocamlc</A></B>(1),<B>&nbsp;<A HREF="/cgi-bin/man/man2html?1+ocamlopt">ocamlopt</A></B>(1),<B>&nbsp;<A HREF="/cgi-bin/man/man2html?1+ocamlrun">ocamlrun</A></B>(1).
<BR>
<I>The&nbsp;OCaml&nbsp;user's&nbsp;manual</I>,
chapter &quot;The toplevel system&quot;.
<P>
<HR>
<A NAME="index">&nbsp;</A><H2>Index</H2>
<DL>
<DT id="38"><A HREF="#lbAB">NAME</A><DD>
<DT id="39"><A HREF="#lbAC">SYNOPSIS</A><DD>
<DT id="40"><A HREF="#lbAD">DESCRIPTION</A><DD>
<DT id="41"><A HREF="#lbAE">OPTIONS</A><DD>
<DT id="42"><A HREF="#lbAF">INITIALIZATION FILE</A><DD>
<DT id="43"><A HREF="#lbAG">ENVIRONMENT VARIABLES</A><DD>
<DT id="44"><A HREF="#lbAH">SEE ALSO</A><DD>
</DL>
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