jocamlc(1) 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, the jocamlc(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 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).

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.
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.

-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 program.

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.

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.

-I directory
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 library directory.

-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.

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.