NAME

       ocaml - The OCaml interactive toplevel

SYNOPSIS

       ocaml [ options ] [ object-files ] [ script-file ]

DESCRIPTION

       The  ocaml(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 # (sharp) prompt before reading each phrase.

       A  toplevel  phrase  can  span  several lines. It is terminated by ;; (a double-semicolon). The syntax of
       toplevel phrases is as follows.

       The toplevel system is started by the command ocaml(1).  Phrases are read on standard input, results  are
       printed on standard output, errors on standard error. End-of-file on standard input terminates ocaml(1).

       If  one or more object-files (ending in .cmo or .cma) are given, they are loaded silently before starting
       the toplevel.

       If a script-file is given, phrases are read silently from the file, errors  printed  on  standard  error.
       ocaml(1) exits after the execution of the last phrase.

OPTIONS

       The following command-line options are recognized by ocaml(1).

       -absname
              Show absolute filenames in error messages.

       -I directory
              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 -I are searched after the current directory, in the order in which they were  given  on
              the command line, but before the standard library directory.

              If  the given directory starts with +, it is taken relative to the standard library directory. For
              instance, -I +compiler-libs adds the subdirectory compiler-libs of the  standard  library  to  the
              search path.

              Directories  can also be added to the search path once the toplevel is running with the #directory
              directive.

       -init file
              Load the given file instead of the default initialization file.  The default file is .ocamlinit in
              the current directory if it exists, otherwise .ocamlinit in the user's home directory.

       -labels
              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.

       -no-app-funct
              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.

       -noassert
              Do  not  compile  assertion  checks.   Note  that the special form assert false is always compiled
              because it is typed specially.

       -nolabels
              Ignore non-optional labels in types. Labels cannot be used in applications,  and  parameter  order
              becomes strict.

       -noprompt
              Do not display any prompt when waiting for input.

       -nopromptcont
              Do  not  display  the  secondary  prompt when waiting for continuation lines in multi-line inputs.
              This should be used e.g. when running ocaml(1) in an emacs(1) window.

       -nostdlib
              Do not include the standard library directory in the list of directories searched for  source  and
              compiled files.

       -open module
              Opens  the given module before starting the toplevel. If several -open options are given, they are
              processed in order, just as if the statements open! module1;; ... open! moduleN;; were input.

       -ppx command
              After parsing, pipe the abstract  syntax  tree  through  the  preprocessor  command.   The  module
              Ast_mapper(3) implements the external interface of a preprocessor.

       -principal
              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 -principal 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.

       -rectypes
              Allow arbitrary recursive types during type-checking.  By default, only recursive types where  the
              recursion goes through an object type are supported.

       -safe-string
              Enforce the separation between types string and bytes, thereby making strings read-only. This will
              become the default in a future version of OCaml.

       -short-paths
              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.

       -stdin Read the standard input as a script file rather than starting an interactive session.

       -strict-sequence
              Force the left-hand part of each sequence to have type unit.

       -unsafe
              Turn bound checking off on array and string  accesses  (the  v.(i)ands.[i]  constructs).  Programs
              compiled  with  -unsafe  are  therefore  slightly  faster,  but unsafe: anything can happen if the
              program accesses an array or string outside of its bounds.

       -unsafe-string
              Identify the types string and bytes, thereby making strings  writable.  For  reasons  of  backward
              compatibility,  this  is  the  default  setting  for  the moment, but this will change in a future
              version of OCaml.

       -version
              Print version string and exit.

       -vnum  Print short version number and exit.

       -w warning-list
              Enable or disable warnings according to the argument warning-list.  See ocamlc(1) for  the  syntax
              of the warning-list argument.

       -warn-error warning-list
              Mark  as  fatal  the  warnings described by the argument warning-list.  Note that a warning is not
              triggered (and does not trigger an error) if it is disabled by the -w option.  See  ocamlc(1)  for
              the syntax of the warning-list argument.

       -warn-help
              Show the description of all available warning numbers.

       - file Use file as a script file name, even when it starts with a hyphen (-).

       -help or --help
              Display a short usage summary and exit.

ENVIRONMENT VARIABLES

       LC_CTYPE
              If  set  to  iso_8859_1,  accented  characters  (from the ISO Latin-1 character set) in string and
              character literals are printed as is; otherwise, they are printed as decimal escape sequences.

       TERM   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.

SEE ALSO

       ocamlc(1), ocamlopt(1), ocamlrun(1).
       The OCaml user's manual, chapter "The toplevel system".

                                                                                                        OCAML(1)