The ocamlmklib tool is an essential part of the OCaml build system, designed to help developers create OCaml libraries. It facilitates the packaging of OCaml code, and potentially C code, into reusable library formats, supporting both static and shared (dynamic) linking.

Creating Static OCaml Libraries

To create a static library, which is typically a single archive file containing all the compiled object code, you can use ocamlmklib with the following syntax. This is a common approach for distributing OCaml code that will be linked directly into an executable.

# Create a static library from OCaml object files
ocamlmklib -o library_name file1.o file2.o

Generating Shared OCaml Libraries

For scenarios requiring dynamic linking, where the library can be loaded at runtime, ocamlmklib supports the creation of shared libraries. This is achieved by using the -shared flag.

# Create a shared library (dynamic linking) from OCaml object files
ocamlmklib -shared -o library_name file1.o file2.o

Integrating C and OCaml Code

ocamlmklib can also be used to build libraries that include both OCaml source files and C source files. The tool will handle the compilation of C files and their integration into the final library.

# Create a library with C files and OCaml files
ocamlmklib -o library_name file1.c file2.ml

Managing Include Paths

When your OCaml or C files depend on modules or headers located in different directories, you can specify these locations using the -I flag to ensure ocamlmklib can find them.

# Include additional directories when searching for files
ocamlmklib -o library_name -I /path/to/dir file1.o file2.o

Specifying Output Directories

You can control where the generated library files and intermediate compilation products are placed using the -oc option, which specifies the output directory.

# Generate a library and specify the output directory for the generated files
ocamlmklib -o library_name -oc /output/directory file1.ml file2.ml

Passing Linker Options

For advanced customization, ocamlmklib allows you to pass specific options directly to the underlying linker using the -ldopts flag. This is useful for fine-tuning the linking process.

# Pass specific options to the linker
ocamlmklib -o library_name -ldopts 'linker_option' file1.o file2.o

Suppressing Informational Messages

To streamline build output, you can use the -quiet flag to suppress non-critical informational messages generated by ocamlmklib.

# Suppress informational messages
ocamlmklib -quiet -o library_name file1.o file2.o

Further Resources

• OCaml Manual - ocamlmklib
• OCaml Compilation Guide