jocamlc - The JoCaml bytecode compiler
jocamlc [ -aciv ] [ -cclib libname ] [ -ccopt option ] [ -custom ] [
-unsafe ] [ -o exec-file ] [ -I lib-dir ] filename ...
jocamlc.opt (same options)
The JoCaml bytecode compiler jocamlc(1) compiles Caml source files to
bytecode object files and link these object files to produce standalone
bytecode executable files. These executable files are then run by the
bytecode interpreter jocamlrun(1).
The jocamlc(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
jocamlc(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 x.ml, the jocamlc(1) compiler
produces compiled object bytecode in the file x.cmo.
If the interface file x.mli exists, the implementation x.ml is checked
against the corresponding compiled interface x.cmi, which is assumed to
exist. If no interface x.mli is provided, the compilation of x.ml
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 and.ml 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 below).
jocamlc.opt is the same compiler as jocamlc, but compiled with the
native-code compiler jocamlopt(1). Thus, it behaves exactly like
jocamlc, but compiles faster. jocamlc.opt is not available in all
installations of JoCaml.
The following command-line options are recognized by jocamlc(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 can be set with the -o
option. The default name is library.cma.
-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
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 program.
-ccopt Pass the given option to the C compiler and linker, when linking
in ‘‘custom runtime’’ mode (see the -custom option). For
instance, -ccopt -L dir causes the C linker to search for C
libraries in directory dir.
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, jocamlrun(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 jocamlrun(1) command is not installed. Moreover, the
‘‘custom runtime’’ mode enables linking Caml code with user-
defined C functions.
-i Cause the compiler to print all defined names (with their
inferred types or their definitions) when compiling an
implementation (.ml file). 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.
Add the given directory to the list of directories searched for
compiled interface files (.cmi) and compiled object code files
(.cmo). 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
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
-v Print the version number of the compiler.
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.
The Objective Caml users manual, chapter "Batch compilation".