Chapter 14 Dependency generator (ocamldep)
The ocamldep command scans a set of OCaml source files
(.ml and .mli files) for references to external compilation units,
and outputs dependency lines in a format suitable for the make
utility. This ensures that make will compile the source files in the
correct order, and recompile those files that need to when a source
file is modified.
The typical usage is:
ocamldep options *.mli *.ml > .depend
where *.mli *.ml expands to all source files in the current
directory and .depend is the file that should contain the
dependencies. (See below for a typical Makefile.)
Dependencies are generated both for compiling with the bytecode
compiler ocamlc and with the native-code compiler ocamlopt.
The following command-line options are recognized by ocamldep.
14.2 A typical Makefile
Show absolute filenames in error messages.
Generate dependencies on all required files, rather than assuming
Allow falling back on a lexer-based approximation when parsing fails.
- -args filename
Read additional newline-terminated command line arguments from filename.
- -args0 filename
Read additional null character terminated command line arguments from filename.
For the following files, do not include delayed dependencies for
This option assumes that they are compiled using options
-no-alias-deps -w -49, and that those files or their interface are
passed with the -map option when computing dependencies for other
files. Note also that for dependencies to be correct in the
implementation of a map file, its interface should not coerce any of
the aliases it contains.
Dump the delayed dependency map for each map file.
- -I directory
Add the given directory to the list of directories searched for
source files. If a source file foo.ml mentions an external
compilation unit Bar, a dependency on that unit’s interface
bar.cmi is generated only if the source for bar is found in the
current directory or in one of the directories specified with -I.
Otherwise, Bar is assumed to be a module from the standard library,
and no dependencies are generated. For programs that span multiple
directories, it is recommended to pass ocamldep the same -I options
that are passed to the compiler.
- -impl file
Process file as a .ml file.
- -intf file
Process file as a .mli file.
- -map file
Read an propagate the delayed dependencies for module aliases in
file, so that the following files will depend on the
exported aliased modules if they use them. See the example below.
- -ml-synonym .ext
Consider the given extension (with leading dot) to be a synonym for .ml.
- -mli-synonym .ext
Consider the given extension (with leading dot) to be a synonym for .mli.
Output raw dependencies of the form
filename: Module1 Module2 ... ModuleN
where Module1, …, ModuleN are the names of the compilation
units referenced within the file filename, but these names are not
resolved to source file names. Such raw dependencies cannot be used
by make, but can be post-processed by other tools such as Omake.
Generate dependencies for a pure native-code program (no bytecode
version). When an implementation file (.ml file) has no explicit
interface file (.mli file), ocamldep generates dependencies on the
bytecode compiled file (.cmo file) to reflect interface changes.
This can cause unnecessary bytecode recompilations for programs that
are compiled to native-code only. The flag -native causes
dependencies on native compiled files (.cmx) to be generated instead
of on .cmo files. (This flag makes no difference if all source files
have explicit .mli interface files.)
Output one line per file, regardless of the length.
- -open module
Assume that module module is opened before parsing each of the
- -pp command
Cause ocamldep to call the given command as a preprocessor
for each source file.
- -ppx command
Pipe abstract syntax trees through preprocessor command.
Generate dependencies for native plugin files (.cmxs) in addition to
native compiled files (.cmx).
Under Windows, use a forward slash (/) as the path separator instead
of the usual backward slash (\). Under Unix, this option does
Sort files according to their dependencies.
Print version string and exit.
Print short version number and exit.
- -help or --help
Display a short usage summary and exit.
Here is a template Makefile for a OCaml program.
INCLUDES= # all relevant -I options here
OCAMLFLAGS=$(INCLUDES) # add other options for ocamlc here
OCAMLOPTFLAGS=$(INCLUDES) # add other options for ocamlopt here
# prog1 should be compiled to bytecode, and is composed of three
# units: mod1, mod2 and mod3.
# The list of object files for prog1
PROG1_OBJS=mod1.cmo mod2.cmo mod3.cmo
$(OCAMLC) -o prog1 $(OCAMLFLAGS) $(PROG1_OBJS)
# prog2 should be compiled to native-code, and is composed of two
# units: mod4 and mod5.
# The list of object files for prog2
$(OCAMLOPT) -o prog2 $(OCAMLFLAGS) $(PROG2_OBJS)
# Common rules
.SUFFIXES: .ml .mli .cmo .cmi .cmx
$(OCAMLC) $(OCAMLFLAGS) -c $<
$(OCAMLC) $(OCAMLFLAGS) -c $<
$(OCAMLOPT) $(OCAMLOPTFLAGS) -c $<
# Clean up
rm -f prog1 prog2
rm -f *.cm[iox]
$(OCAMLDEP) $(INCLUDES) *.mli *.ml > .depend
If you use module aliases to give shorter names to modules, you need
to change the above definitions. Assuming that your map file is called
mylib.mli, here are minimal modifications.
OCAMLFLAGS=$(INCLUDES) -open Mylib
$(OCAMLC) $(INCLUDES) -no-alias-deps -w -49 -c $<
$(OCAMLDEP) $(INCLUDES) -map mylib.mli $(PROG1_OBJS:.cmo=.ml) > .depend
Note that in this case you should not compute dependencies for
mylib.mli together with the other files, hence the need to pass
explicitly the list of files to process.
If mylib.mli itself has dependencies, you should compute them using