ocaml - The OCaml interactive toplevel

       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  standard
       input,  then  typechecks, compiles and evaluates them, then prints the inferred type and result value, if
       any.  End-of-file on standard input terminates ocaml(1).

       Input to the toplevel can span several lines. It begins after the # (sharp) prompt printed by the  system
       and  is  terminated  by ;; (a double-semicolon) followed by optional white space and an end of line.  The
       toplevel input consists in one or several toplevel phrases.

       If one or more object-files (ending in .cmo or .cma) are given on  the  command  line,  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.

OCAMLTOP_UTF_8
              When printing string values, non-ascii bytes (>0x7E) are printed as  decimal  escape  sequence  if
              OCAMLTOP_UTF_8 is set to false. Otherwise they are printed unescaped.

       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.

       XDG_CONFIG_HOMEHOMEXDG_CONFIG_DIRS
              See INITIALIZATIONFILE above.

       When ocaml(1) is invoked, it will read phrases from an initialization file before giving control  to  the
       user. The file read is the first found of:

       1.     .ocamlinit in the current directory;

       2.     XDG_CONFIG_HOME/ocaml/init.ml, if XDG_CONFIG_HOME is an absolute path;

       3.     otherwise,  on  Unix,  HOME/ocaml/init.ml  or,  on Windows, ocaml\init.ml under LocalAppData (e.g.
              C:\Users\Bactrian\AppData\Local\ocaml\init.ml);

       4.     ocaml/init.ml under any of the absolute paths in XDG_CONFIG_DIRS.  Paths  in  XDG_CONFIG_DIRS  are
              colon-delimited on Unix, and semicolon-delimited on Windows;

       5.     if  XDG_CONFIG_DIRS  contained no absolute paths, /usr/xdg/ocaml/init.ml on Unix or, ocaml\init.ml
              under  any  of   LocalAppData   (e.g.   C:\Users\Bactrian\AppData\Local),   RoamingAppData   (e.g.
              C:\Users\Bactrian\AppData\Roaming), or ProgramData (e.g. C:\ProgramData) on Windows;

       6.     HOME/.ocamlinit, if HOME is non-empty;

              You  can  specify  a  different  initialization  file  by using the -initfile option, and disable
              initialization files by using the -noinit option.

              Note that you can also use the #use directive to read phrases from a file.

       ocaml - The OCaml interactive toplevel

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

       -absname
              Show absolute filenames in error messages.

       -no-absname
              Do not try to show absolute filenames in error messages.

       -Idirectory
              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.

       -initfile
              Load  the  given  file  instead of the default initialization file.  See the "Initialization file"
              section below.

       -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 assertfalse is always compiled
              because it is typed specially.

       -noinit
              Do not load any initialization file.  See the "Initialization file" section below.

       -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.

       -openmodule
              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.

       -ppxcommand
              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.

       -no-principal
              Do not check principality of type inference.  This is the default.

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

       -no-rectypes
              Do no allow arbitrary recursive types during type-checking.  This is the default.

       -safe-string
              Enforce  the  separation between types string and bytes, thereby making strings read-only. This is
              the default.

       -safer-matching
              Do not use type information to optimize pattern-matching.  This allows to  detect  match  failures
              even  if  a  pattern-matching  was  wrongly  assumed  to be exhaustive. This only impacts GADT and
              polymorphic variant compilation.

       -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.

       -no-strict-sequence
              Left-hand part of a sequence need not have type unit.  This is the default.

       -unboxed-types
              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 [@@ocaml.boxed].

       -no-unboxed-types
              When a type is unboxable  it will be boxed unless annotated with [@@ocaml.unboxed].  This  is  the
              default.

       -unsafe
              Turn  bound  checking  off on array and string accesses (the v.(i) and s.[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.  This is intended for
              compatibility with old source code and should not be used with new software.

       -version
              Print version string and exit.

       -vnum  Print short version number and exit.

       -no-version
              Do not print the version banner at startup.

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

       -warn-errorwarning-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.

       -colormode
              Enable  or  disable  colors  in compiler messages (especially warnings and errors).  The following
              modes are supported:

              auto use heuristics to enable colors only if the output  supports  them  (an  ANSI-compatible  tty
              terminal);

              always enable colors unconditionally;

              never disable color output.

              The  environment  variable  "OCAML_COLOR"  is considered if -color is not provided. Its values are
              auto/always/never as above.

              If -color is not provided, "OCAML_COLOR" is not set and the  environment  variable  "NO_COLOR"  is
              set,  then  color  output  is  disabled.  Otherwise,  the default setting is auto, and the current
              heuristic checks that the "TERM" environment variable exists and is not empty or "dumb", and  that
              isatty(stderr) holds.

       -error-stylemode
              Control the way error messages and warnings are printed.  The following modes are supported:

              short only print the error and its location;

              contextual like "short", but also display the source code snippet corresponding to the location of
              the error.

              The default setting is contextual.

              The  environment  variable  "OCAML_ERROR_STYLE" is considered if -error-style is not provided. Its
              values are short/contextual as above.

       -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.

ocamlc(1), ocamlopt(1), ocamlrun(1).
       TheOCamluser'smanual, chapter "The toplevel system".

                                                                                                        OCAML(1)

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