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       ocamlc - The Objective Caml bytecode compiler


       ocamlc [ options ] filename ...

       ocamlc.opt [ options ] filename ...


       The  Objective  Caml  bytecode  compiler  ocamlc(1) compiles Caml source files to bytecode
       object files and links these object files to produce standalone bytecode executable files.
       These executable files are then run by the bytecode interpreter ocamlrun(1).

       The ocamlc(1) command has a command-line interface similar to the one of most C compilers.
       It accepts several types of arguments and processes them sequentially:

       Arguments ending in .mli are taken to be source files  for  compilation  unit  interfaces.
       Interfaces  specify the names exported by compilation units: they declare value names with
       their types, define public data types, declare abstract data types, and so  on.  From  the
       file x.mli, the ocamlc(1) compiler produces a compiled interface in the file x.cmi.

       Arguments ending in .ml are taken to be source files for compilation unit implementations.
       Implementations provide definitions for the names exported by the unit, and  also  contain
       expressions  to  be  evaluated  for their side-effects.  From the file, the ocamlc(1)
       compiler produces compiled object bytecode in the file x.cmo.

       If the interface file x.mli  exists,  the  implementation  is  checked  against  the
       corresponding  compiled  interface x.cmi, which is assumed to exist. If no interface x.mli
       is provided, the compilation of produces a compiled interface file x.cmi in  addition
       to  the  compiled  object  code  file  x.cmo.   The  file x.cmi produced corresponds to an
       interface that exports everything that is defined in the implementation

       Arguments ending in .cmo are taken to be compiled object bytecode.  These files are linked
       together,  along  with  the object files obtained by compiling .ml arguments (if any), and
       the Caml Light standard library, to produce a standalone executable program. The order  in
       which  .cmo  arguments  are presented on the command line is relevant: compilation
       units are initialized in that order at run-time, and it is a  link-time  error  to  use  a
       component  of  a  unit  before  having initialized it. Hence, a given x.cmo file must come
       before all .cmo files that refer to the unit x.

       Arguments ending in .cma are taken to be libraries  of  object  bytecode.   A  library  of
       object  bytecode  packs  in  a  single  file  a set of object bytecode files (.cmo files).
       Libraries are built with ocamlc -a (see the description  of  the  -a  option  below).  The
       object files contained in the library are linked as regular .cmo files (see above), in the
       order specified when the .cma file was built. The only difference is  that  if  an  object
       file  contained  in  a  library  is not referenced anywhere in the program, then it is not
       linked in.

       Arguments ending in .c are passed to the C compiler, which generates  a  .o  object  file.
       This  object  file  is  linked  with  the  program  if  the  -custom  flag is set (see the
       description of -custom below).

       Arguments ending in .o or .a are assumed to be C object  files  and  libraries.  They  are
       passed  to  the  C  linker  when  linking  in -custom mode (see the description of -custom

       Arguments ending in .so are assumed to be C shared libraries (DLLs).  During linking, they
       are  searched  for external C functions referenced from the Caml code, and their names are
       written in the generated bytecode executable.  The run-time system ocamlrun(1) then  loads
       them dynamically at program start-up time.

       The  output  of  the  linking  phase  is  a  file containing compiled bytecode that can be
       executed by the Objective Caml bytecode interpreter: the command ocamlrun(1).  If caml.out
       is  the  name  of  the  file  produced by the linking phase, the command ocamlrun caml.out
       arg1  arg2 ... argn executes the compiled  code  contained  in  caml.out,  passing  it  as
       arguments the character strings arg1 to argn.  (See ocamlrun(1) for more details.)

       On  most  systems,  the  file  produced  by  the linking phase can be run directly, as in:
       ./caml.out arg1  arg2 ... argn.  The produced file has the  executable  bit  set,  and  it
       manages to launch the bytecode interpreter by itself.

       ocamlc.opt  is  the  same  compiler  as ocamlc, but compiled with the native-code compiler
       ocamlopt(1).  Thus, it behaves exactly like ocamlc, but compiles faster.   ocamlc.opt  may
       not be available in all installations of Objective Caml.


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

       -a     Build a library (.cma file) with the object files (.cmo files) given on the command
              line, instead of linking them into an executable file. The name of the library must
              be set with the -o option.

              If  -custom, -cclib or -ccopt options are passed on the command line, these options
              are stored in  the  resulting  .cma  library.   Then,  linking  with  this  library
              automatically  adds back the -custom, -cclib and -ccopt options as if they had been
              provided on the command line, unless the -noautolink option is given.

       -annot Dump detailed information about the compilation (types, bindings, tail-calls, etc).
              The  information  for  file  is put into file src.annot.  In case of a type
              error, dump all the information inferred by the type-checker before the error.  The
              src.annot  file can be used with the emacs commands given in emacs/caml-types.el to
              display types and other annotations interactively.

       -c     Compile only. Suppress the linking phase of the compilation. Source code files  are
              turned  into  compiled  files,  but  no executable file is produced. This option is
              useful to compile modules separately.

       -cc ccomp
              Use ccomp as the C linker when linking in "custom runtime" mode  (see  the  -custom
              option) and as the C compiler for compiling .c source files.

       -cclib -llibname
              Pass  the  -llibname  option  to the C linker when linking in "custom runtime" mode
              (see the -custom option). This causes the given C library to  be  linked  with  the

       -ccopt Pass  the  given  option  to  the  C  compiler  and linker, when linking in "custom
              runtime" mode (see the -custom option). For instance,  -ccopt -Ldir  causes  the  C
              linker to search for C libraries in directory dir.

              Print  the version number of ocamlc(1) and a detailed summary of its configuration,
              then exit.

              Link in "custom runtime" mode. In the default linking  mode,  the  linker  produces
              bytecode  that  is  intended  to  be  executed  with  the  shared  runtime  system,
              ocamlrun(1).  In the custom runtime mode, the linker produces an output  file  that
              contains  both  the  runtime system and the bytecode for the program. The resulting
              file is larger, but it can be executed directly, even if the ocamlrun(1) command is
              not  installed.  Moreover, the "custom runtime" mode enables linking Caml code with
              user-defined C functions.

              Never use the strip(1) command on  executables  produced  by  ocamlc -custom,  this
              would remove the bytecode part of the executable.

       -dllib -llibname
              Arrange for the C shared library to be loaded dynamically by the run-
              time system ocamlrun(1) at program start-up time.

       -dllpath dir
              Adds the directory dir to the run-time search path  for  shared  C  libraries.   At
              link-time,  shared  libraries  are  searched  in  the standard search path (the one
              corresponding to the -I option).  The -dllpath option  simply  stores  dir  in  the
              produced executable file, where ocamlrun(1) can find it and use it.

       -g     Add  debugging  information while compiling and linking. This option is required in
              order to be able to debug the program  with  ocamldebug(1)  and  to  produce  stack
              backtraces when the program terminates on an uncaught exception.

       -i     Cause  the  compiler to print all defined names (with their inferred types or their
              definitions) when compiling an implementation (.ml file). No compiled  files  (.cmo
              and  .cmi  files)  are produced.  This can be useful to check the types inferred by
              the compiler. Also, since the output follows the syntax of interfaces, it can  help
              in writing an explicit interface (.mli file) for a file: just redirect the standard
              output of the  compiler  to  a  .mli  file,  and  edit  that  file  to  remove  all
              declarations of unexported names.

       -I directory
              Add  the given directory to the list of directories searched for compiled interface
              files (.cmi), compiled object code files (.cmo), libraries (.cma), and C  libraries
              specified with -cclib -l xxx.  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 +labltk adds the subdirectory labltk of the standard
              library to the search path.

       -impl filename
              Compile the file filename as an implementation file, even if its extension  is  not

       -intf filename
              Compile the file filename as an interface file, even if its extension is not .mli.

       -intf-suffix string
              Recognize  file names ending with string as interface files (instead of the default

              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.

              Force  all  modules  contained  in  libraries  to be linked in. If this flag is not
              given, unreferenced modules are not linked in. When building a library (option -a),
              setting  the -linkall option forces all subsequent links of programs involving that
              library to link all the modules contained in the library.

              Build a custom runtime system (in the file specified by  option  -o)  incorporating
              the  C  object  files and libraries given on the command line.  This custom runtime
              system can be used later to execute bytecode executables produced with  the  option
              ocamlc -use-runtime runtime-name.

              Do not compile assertion checks.  Note that the special form assert false is always
              compiled because it is typed specially.  This  flag  has  no  effect  when  linking
              already-compiled files.

              When  linking .cma libraries, ignore -custom, -cclib and -ccopt options potentially
              contained in  the  libraries  (if  these  options  were  given  when  building  the
              libraries).  This can be useful if a library contains incorrect specifications of C
              libraries or C options; in this case, during linking, set -noautolink and pass  the
              correct C libraries and options on the command line.

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

       -o exec-file
              Specify the name of the output file produced by the linker. The default output name
              is  a.out,  in  keeping with the Unix tradition. If the -a option is given, specify
              the name of the library produced.  If the -pack option is given, specify  the  name
              of  the  packed  object file produced.  If the -output-obj option is given, specify
              the name of the output file produced.

              Cause the linker to produce a C object file instead of a bytecode executable  file.
              This  is  useful to wrap Caml code as a C library, callable from any C program. The
              name of the output object file is camlprog.o by default; it can be set with the  -o
              option. This option can also be used to produce a C source file (.c extension) or a
              compiled shared/dynamic library (.so extension).

       -pack  Build a bytecode object file (.cmo file)  and  its  associated  compiled  interface
              (.cmi) that combines the object files given on the command line, making them appear
              as sub-modules of the output .cmo file.  The name of the output .cmo file  must  be
              given  with  the  -o option.  For instance, ocamlc -pack -o p.cmo a.cmo b.cmo c.cmo
              generates compiled files p.cmo and p.cmi describing a compilation unit having three
              sub-modules  A,  B  and C, corresponding to the contents of the object files a.cmo,
              b.cmo and c.cmo.  These contents can be referenced as  P.A,  P.B  and  P.C  in  the
              remainder of the program.

       -pp command
              Cause  the  compiler  to  call  the given command as a preprocessor for each source
              file. The output of command  is  redirected  to  an  intermediate  file,  which  is
              compiled.  If  there  are  no  compilation errors, the intermediate file is deleted
              afterwards. The name of this file is built from the basename  of  the  source  file
              with the extension .ppi for an interface (.mli) file and .ppo for an implementation
              (.ml) file.

              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.

              Allow arbitrary recursive types during type-checking.  By default,  only  recursive
              types where the recursion goes through an object type are supported. Note that once
              you have created an interface using this flag,  you  must  use  it  again  for  all

              Compile  or  link  multithreaded programs, in combination with the system "threads"
              library described in The Objective Caml user's manual.

              Turn  bound  checking  off  for  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.

       -use-runtime runtime-name
              Generate  a  bytecode  executable  file  that can be executed on the custom runtime
              system runtime-name, built earlier with ocamlc -make-runtime runtime-name.

       -v     Print the version number of the compiler and the location of the  standard  library
              directory, then exit.

              Print  all external commands before they are executed, in particular invocations of
              the C compiler and linker in -custom mode.  Useful to debug C library problems.

              Print the version number of the compiler in short form (e.g. "3.11.0"), then exit.

              Compile or link multithreaded programs, in combination with  the  VM-level  threads
              library described in The Objective Caml user's manual.

       -w warning-list
              Enable,  disable,  or  mark  as  errors  the  warnings  specified  by  the argument

              Each warning can be enabled or disabled, and each warning can be marked (as  error)
              or  unmarked.   If  a  warning  is  disabled, it isn't displayed and doesn't affect
              compilation in any way (even if it is marked).  If a  warning  is  enabled,  it  is
              displayed  normally by the compiler whenever the source code triggers it.  If it is
              enabled and marked, the compiler will stop  with  an  error  after  displaying  the
              warnings if the source code triggers it.

              The  warning-list  argument is a sequence of warning specifiers, with no separators
              between them.  A warning specifier is one of the following:

              +num   Enable warning number num.

              -num   Disable warning number num.

              @num   Enable and mark warning number num.

              +letter   Enable the set of warnings corresponding to letter.  The  letter  may  be
              uppercase or lowercase.

              -letter    Disable  the set of warnings corresponding to letter.  The letter may be
              uppercase or lowercase.

              @letter   Enable and mark the set of warnings corresponding to letter.  The  letter
              may be uppercase or lowercase.

              uppercase-letter   Enable the set of warnings corresponding to uppercase-letter.

              lowercase-letter   Disable the set of warnings corresponding to lowercase-letter.

              The warning numbers are as follows.

              1    Suspicious-looking start-of-comment mark.

              2    Suspicious-looking end-of-comment mark.

              3    Deprecated syntax.

              4     Fragile  pattern  matching:  matching  that  will  remain  complete  even  if
              additional constructors are added to one of the variant types matched.

              5    Partially applied function: expression whose result has function type  and  is

              6    Label omitted in function application.

              7    Some methods are overridden in the class where they are defined.

              8    Partial match: missing cases in pattern-matching.

              9    Missing fields in a record pattern.

              10    Expression  on  the  left-hand side of a sequence that doesn't have type unit
              (and that is not a function, see warning number 5).

              11   Redundant case in a pattern matching (unused match case).

              12   Redundant sub-pattern in a pattern-matching.

              13   Override of an instance variable.

              14   Illegal backslash escape in a string constant.

              15   Private method made public implicitly.

              16   Unerasable optional argument.

              17   Undeclared virtual method.

              18   Non-principal type.

              19   Type without principality.

              20   Unused function argument.

              21   Non-returning statement.

              22   Camlp4 warning.

              23   Useless record with clause.

              24   Bad module name: the source file name is not a valid OCaml module name.

              25   Pattern-matching with all clauses guarded.

              26   Suspicious unused variable: unused variable that is bound with let or as,  and
              doesn't start with an underscore (_) character.

              27    Innocuous unused variable: unused variable that is not bound with let nor as,
              and doesn't start with an underscore (_) character.

              28   A pattern contains a  constant  constructor  applied  to  the  underscore  (_)

              29   A non-escaped end-of-line was found in a string constant.  This may

              cause portability problems between Unix and Windows.

              The  letters  stand  for  the following sets of warnings.  Any letter not mentioned
              here corresponds to the empty set.

              A  all warnings

              C  1, 2

              D  3

              E  4

              F  5

              L  6

              M  7

              P  8

              R  9

              S  10

              U  11, 12

              V  13

              X  14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25

              Y  26

              Z  27

              The default setting is -w +a-4-6-9-27-28-29.  Note that warnings 5 and 10  are  not
              always triggered, depending on the internals of the type checker.

       -warn-error warning-list
              Mark  as  errors the warnings specified in the argument warning-list.  The compiler
              will stop with an error when one of these warnings is  emitted.   The  warning-list
              has  the same meaning as for the -w option: a + sign (or an uppercase letter) turns
              the corresponding warnings into errors, a - sign (or a lowercase letter) turns them
              back into warnings, and a @ sign both enables and marks the corresponding warnings.

              Note:  it  is  not  recommended  to use warning sets (i.e. letters) as arguments to
              -warn-error in production code, because this  can  break  your  build  when  future
              versions of OCaml add some new warnings.

              The  default  setting  is  -warn-error +a  (none  of  the warnings is treated as an

       -where Print the location of the standard library, then exit.

       - file Process file as a file name, even if it starts with a dash (-) character.

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


       ocamlopt(1), ocamlrun(1), ocaml(1).
       The Objective Caml user's manual, chapter "Batch compilation".