module Topkg:sig..end
In the most simple cases you won't need this, jump directly to the basics or package description API.
val (>>=) : ('a, 'b) Stdlib.result ->
('a -> ('c, 'b) Stdlib.result) -> ('c, 'b) Stdlib.resultr >>= f is f v if r = Ok v and r if r = Error _.
val (>>|) : ('a, 'b) Stdlib.result -> ('a -> 'c) -> ('c, 'b) Stdlib.resultr >>| f is Ok (f v) if r = Ok v and r if r = Error _.
type('a, 'b)r =('a, 'b) Stdlib.result=
| |
Ok of |
| |
Error of |
This definition re-export result's constructors so that an
open Topkg gets them in scope.
type'aresult =('a, [ `Msg of string ]) r
The type for topkg results.
module R:sig..end
Result value combinators.
val strf : ('a, Stdlib.Format.formatter, unit, string) Stdlib.format4 -> 'astrf is Printf.asprintf.
module String:sig..end
Strings.
typefpath =string
The type for file system paths.
module Fpath:sig..end
File system paths.
module Cmd:sig..end
Command lines.
module Log:sig..end
Topkg log.
module OS:sig..end
OS interaction.
module Vcs:sig..end
Version control system repositories.
module Conf:sig..end
Build configuration.
module Exts:sig..end
Exts defines sets of file extensions.
module Pkg:sig..end
Package description.
module Private:sig..end
Private definitions.
Topkg is a packager for distributing OCaml software. Fundamentally
it only provides a simple and flexible mechanism to describe an opam
install
file according to the build configuration which is used to infer one
corresponding invocation of your build system.
This simple idea brings the following advantages:
opam-installer tool or anything that understands an opam
install file.Beyond this a Topkg package description provides information about
the package's distribution creation and publication procedures. This
enables swift and correct package distribution management via the topkg
tool, see Package care.
The root of you source repository should have the following layout:
pkg/pkg.ml, the package description written with Topkg's API.
See package description.pkg/META, an
ocamlfind
META file describing your package. See Topkg.Pkg.describe to configure this._tags, ocamlbuild file with at least a true : bin_annot line.
See handling cmt and cmti files for details.opam, the package's opam metadata. See opam and package build instructions.README.md, your readme file. See Topkg.Pkg.describe to configure this.LICENSE.md, your license file. See Topkg.Pkg.describe to configure this.CHANGES.md, your change log. See Topkg.Pkg.describe to configure this.If you start a new library
carcass can generate
the structural boilerplate with your personal information and preferences.
Invoke:
carcass body topkg/pkg mypkg (cd mypkg && git init && git add . && git commit -m "First commit.") opam pin add -kgit mypkg mypkg#master
and you have a library that is {opam,ocamlfind}-able with correct
version watermarks on releases and opam pins. You are now only a few
invocations away to release it in the OCaml opam repository, see
topkg help release for doing so; but don't forget to document it and
make it do something useful.
The package needs to build-depend on topkg as well as ocamlfind
which is used by the package description file pkg/pkg.ml to find the
topkg library; it is likely that you are using ocamlbuild too. So
the depends field of your opam file should at least have:
depends: [
"ocamlfind" {build}
"ocamlbuild" {build}
"topkg" {build & >= 0.9.0} ]
The build instructions of the package are simply an invocation of
pkg/pkg.ml with the build command and a specification of the
build configuration on the command line. In the simplest case, if
your package has no configuration options, this simply boils
down to:
# For opam >= 2.0
build: [[ "ocaml" "pkg/pkg.ml" "build" "--dev-pkg" "%{dev}%" ]]
# For opam < 2.0
build: [[ "ocaml" "pkg/pkg.ml" "build" "--dev-pkg" "%{pinned}%" ]]
The "--dev-pkg" configuration key is used to inform the package
description about the build context. This
invocation of pkg/pkg.ml executes your build system with a set of
targets determined from the build configuration and generates in the
root directory of your distribution an opam install file that opam
uses to install and uninstall your package.
This is all you need to specify. Do not put anything in the remove
field of the opam file. Likewise there is no need to invoke
ocamlfind with your META file. Your META file should simply be
installed in the directory of the lib field which happens
automatically by default.
If you described tests then you should specify the instructions as follows (unfortunately for opam < 2.0 this involves the repetition of the build line):
# For opam >= 2.0
build:
[[ "ocaml" "pkg/pkg.ml" "build" "--dev-pkg" "%{dev}%"
"--tests" "%{build-test}%" ]]
run-test:
[[ "ocaml" "pkg/pkg.ml" "test" ]]
# For opam < 2.0
build:
[[ "ocaml" "pkg/pkg.ml" "build" "--dev-pkg" "%{pinned}%" ]]
build-test:
[[ "ocaml" "pkg/pkg.ml" "build" "--dev-pkg" "%{pinned}%" "--tests" "true" ]
[ "ocaml" "pkg/pkg.ml" "test" ]]
Beyond opam. If you need to support another package system you
can invoke pkg/pkg.ml as above and then manage the installation and
uninstallation at a given $DESTDIR with the generated opam install
file using opam-installer tool or any other program that understand
these files.
The Topkg.Pkg.describe function has a daunting number of arguments and
configuration options. However if you keep things simple and stick to
the defaults, much of this does not need to be specified.
For example, if we consider the basic setup mentioned
above for a library described with an OCamlbuild src/mylib.mllib
file, your package description file pkg/pkg.ml simply looks like
this:
#!/usr/bin/env ocaml
#use "topfind"
#require "topkg"
open Topkg
let () =
Pkg.describe "mylib" @@ fun c ->
Ok [ Pkg.mllib "src/mylib.mllib" ]
Tip. To allow
merlin to function
correctly in your package description, issue M-x merlin-use topkg in
emacs or :MerlinUse topkg in vim.
This simple description builds and installs the library described by
the src/mylib.mllib file. It works correctly if native code
compilation or native dynamic linking is not available. It
automatically installs the package's META file in the directory of the
lib field and your readme, change log and license file in the
directory of the doc field.
Try to test the package build description with topkg build, this
builds the package according to the description and build
configuration and writes a mylib.install at the root of the
distribution that describes the package installation. If everything
went well, you are now ready to release, see topkg help release for
the procedure.
To debug package descriptions it useful to dry run the build. This
prevents the package from building and only writes the mylib.install file
determined according to the build configuration.
topkg build -d # Only write the opam install file
topkg build -d -v # Also print the build configuration
topkg help troubleshoot # More troubleshooting tips
Note that topkg build does nothing more than invoke
ocaml "pkg/pkg.ml" build. If you would like to see the build
configuration
options of a package description you should do:
ocaml pkg/pkg.ml help ./pkg/pkg.ml help # If has exec right
An opam install file is a description of a standard UNIX install. It
has fields for each of the standard directories lib, bin, man,
etc, etc. Each of these fields lists the files to install in the
corresponding directory (or subdirectories). See the
install file
specification in the opam developer manual for more information.
A topkg install description is just a convenient and compact way to describe an opam install file according to the build configuration. In turn this also describes what needs to be built which allows topkg to call the build system appropriately.
For each opam install field there is a corresponding field function
that you can use to generate install moves. The documentation of
Topkg.Pkg.field and Topkg.Pkg.exec_field describes how you can use or omit
their various arguments to simplify the description. Topkg also provides
a few higher-level convenience functions like Topkg.Pkg.mllib and
Topkg.Pkg.clib which allow to reuse the description work already done
for OCamlbuild.
In the following we review a few basic install use cases. The menagerie provides links to full and more complex examples.
It is possible to use the Topkg.Pkg.lib field function and appropriate
file extensions to manually install a library, but this
quickly becomes tedious. The higher-level Topkg.Pkg.mllib install function
brings this to a single line by reading from a OCamlbuild mllib file.
Given a library described in src/mylib.mllib file use:
Pkg.mllib "src/mylib.mllib"
This will make all the modules mentioned in the mllib file part of
the API (i.e. install its cmi files). You can restrict
the API by using the ~api optional argument. In the following, only
Mod1 and Mod2 define the API, the other modules of mllib remain hidden
to the end user (but unfortunately not to the linkers...):
Pkg.mllib ~api:["Mod1"; "Mod2"] "src/myllib.mllib"
A shortcut also exists for installing C stubs: Topkg.Pkg.clib. Simply use
it on an existing src/libmystub.clib file (N.B. OCamlbuild
mandates that your clib file name starts with lib):
Pkg.clib "src/libmystub.clib"
This will generate the appropriate install moves in the lib and stublib
fields.
In opam, binaries can only be installed by using the bin, sbin and
libexec fields. Trying to install a binary in other fields will not
set its executable bit
(discussion).
Most of the time one wants to install native binaries if native code
compilation is available and bytecode ones if it is not. The auto
argument of Topkg.Pkg.exec_field does exactly this if omited.
So if you have an executable to install in the bin field whose main
is in src/myexec.ml, describe it with:
Pkg.bin "src/myexec"
As with any other field it easy to rename the executable along the
way with the dst argument:
Pkg.bin "src/myexec" ~dst:"my-exec"
Note that using the default value of auto also automatically handles
the extension business for Windows platforms.
An easy and readable way to handle conditional installs is to use the
cond argument of field functions. The following shows
how to conditionaly build and install a binary depending on the opam
cmdliner package being installed:
let cmdliner = Conf.with_pkg "cmdliner"
let () =
Pkg.describe "mypkg" @@ fun c ->
let cmdliner = Conf.value c cmdliner in
Ok [ Pkg.bin ~cond:cmdliner "src/myexec" ]
Note that configuration keys must be created before the
call to Topkg.Pkg.describe. Their value can then be accessed with the
Topkg.Conf.value from the configuration given to the install move
function you specify.
For this conditional install the opam build instructions look like this:
depopts: [ "cmdliner" ]
build: [[
"ocaml" "pkg/pkg.ml" "build"
"--dev-pkg" "%{dev}%" # use "%{pinned}%" for opam < 2.0
"--with-cmdliner" cmdliner:installed ]]
Some conditions related to native code and native code dynamic linking
happen automatically. For example moves with paths ending with .cmxs
are automatically dropped if Topkg.Conf.OCaml.native_dynlink is false
in the current build configuration. This behaviour can be disabled by
using the force argument of field functions.
The field functions have an optional exts argument. If
present these extensions are appended to the src path given to the
function. The module Topkg.Exts defines a few predefined extension
sets. For example a single module library archive implemented in
src/mylib.ml can be declared by:
Pkg.lib ~exts:Exts.module_library "src/mylib"
which is, effectively, a shortcut for:
[ Pkg.lib "src/mylib.mli";
Pkg.lib "src/mylib.cmti";
Pkg.lib "src/mylib.cmi";
Pkg.lib "src/mylib.cmx";
Pkg.lib "src/mylib.cma";
Pkg.lib "src/mylib.a";
Pkg.lib "src/mylib.cmxa";
Pkg.lib "src/mylib.cmxs"; ]
Extensions sets are also used to support platform independent installs. For example to install a static C library archive you should use the second invocation, not the first one:
Pkg.lib "src/libmylib.a" (* DON'T do this *)
Pkg.lib ~exts:Exts.c_library "src/libmylib" (* Do this *)
this ensures that the correct, platform dependent, suffix is used.
By default install moves simply install the file at the root directory
of the field. Using the dst optional argument you can rename the file and/or
install it to subdirectories.
Pkg.lib "src/b.cmo" ~dst:"hey" (* Install as [hey] file. *)
Pkg.lib "src/b.cmo" ~dst:"hey/" (* Install in [hey] subdirectory *)
Pkg.lib "src/b.cmo" ~dst:"hey/ho.cmo" (* Install as [ho.cmo] in [hey]. *)
Since the OCaml tools generate .cmt and .cmti files only as a side
effect they are treated specially: they are not built. For
OCamlbuild you should add this line to your _tags file:
true : bin_annot
this will build them as a side effect of other build invocations. In
the generated opam install file the cmt and cmti files are
prefixed by a ? so that if they are not built the install does not
fail.
Developing and distributing packages implies a lot of mundane but
nevertheless important tasks. The topkg tool, guided by information
provided by Topkg.Pkg.describe helps you with these tasks.
For example topkg lint makes sure that the package source repository
or distribution follows a few established (or your) conventions and
that the META and opam files of the package pass their respective
linter. topkg distrib will create watermarked and reproducible
distribution archives (see Topkg.Pkg.distrib) while topkg publish and
topkg opam will help publishing them. All this and more is described
with details in topkg's help system, invoke:
topkg help release topkg help
to get an extended introduction and pointers to these features.
Topkg provides support to make it easier to write and publish your
package documentation. The topkg doc -r command generates and refreshes
renderings of the package documentation while you work on it.
Documentation publication is always derived from a generated distribution archive (the latter doesn't need to be published of course). So to push documentation fixes and clarifications simply invoke:
topkg distrib topkg publish doc
Make sure you include %%VERSION%% watermarks in the documentation so that readers know exactly which version they are reading. By default this will be substituted by a VCS tag description so it will be precise even though you may not have properly tagged a new release for the package.
The following sample setup shows how to store build configuration information in build artefacts.
In this example we store the location of the install's etc directory
in the build artefacts. The setup also works seamlessly during
development if build artefacts are invoked from the root directory of
the source repository.
We have the following file layout in our source repository:
etc/mypkg.conf # Configuration file src/mypkg_etc.ml # Module with path to the etc dir
the contents of src/mypkg_etc.ml is simply:
(* This file is overwritten by distribution builds. During development
it refers to the [etc] directory at the root directory of the
source repository. *)
let dir = "etc"
the value Mypkg_etc.dir is used in the sources to refer to the etc
directory of the install. In the package description file
pkg/pkg.ml we have the following lines:
let (* 1 *) etc_dir =
let doc = "Use $(docv) as the etc install directory" in
Conf.(key "etc-dir" fpath ~absent:"etc" ~doc)
let (* 2 *) etc_config c = match Conf.build_context c with
| `Dev -> Ok () (* Do nothing, the repo src/mypkg_etc.ml will do *)
| `Pin | `Distrib ->
let config = strf "let dir = %S" (Conf.value c etc_dir) in
OS.File.write "src/mypkg_etc.ml" config
let () =
let build = Pkg.build ~pre:etc_config () in
Pkg.describe "mypkg" ~build @@ fun c ->
Ok [ (* 3 *) Pkg.etc "etc/mpypkg.conf"; ... ]
In words:
"etc-dir" that holds the location
of the install etc directory.src/mypkg_etc.ml with its actual value on `Pin and `Distrib builds.etc/mypkg.conf configuration in the install etc
directory.The opam build instructions for the package are:
build: [[
"ocaml" "pkg/pkg.ml" "build"
"--dev-pkg" "%{dev}%" # use "%{pinned}%" for opam < 2.0
"--etc-dir" mypkg:etc ]]
It is not too hard to define multiple opam packages for the same
distribution. Topkg itself
uses this
trick to manage its dependencies between topkg and topkg-care.
To achieve this your package description file can simply condition
the package install description on the package name
communicated by the configuration. In this setup
you'll likely have one $PKG.opam per $PKG at the root of your source
repository, you should declare them in the description too, so that
they get properly linted and used by the topkg tool when appropriate
(see how the opam file is looked up according to the package name
in Topkg.Pkg.describe). Here is a blueprint:
let () =
let opams =
let install = false in
[ Pkg.opam_file ~install "mypkg-main.opam";
Pkg.opam_file ~install "mypkg-snd.opam"; ]
in
Pkg.describe ~opams "mypkg-main" @@ fun c ->
match Conf.pkg_name c with
| "mypkg-main" ->
Ok [ Pkg.lib "mypkg-main.opam" ~dst:"opam";
(* mypkg-main install *) ]
| "mypkg-snd" ->
Ok [ Pkg.lib "mypkg-snd.opam" ~dst:"opam";
(* mypkg-snd install *) ]
| other ->
R.error_msgf "unknown package name: %s" other
The build instructions of these opam files need to give the name of the package to the build invocation so that the right install description can be selected:
build: [[
"ocaml" "pkg/pkg.ml" "build"
"--pkg-name" name
"--dev-pkg" "%{dev}%" # use "%{pinned}%" for opam < 2.0
]]
In general you will use the default, main, package name and its opam file to create and publish the distribution archive file and all packages will use the same distribution; the opam packages will only differ in their opam file. Releasing the set of packages then becomes:
# Release the distribution and base package (use topkg bistro
# for doing this via a single invocation)
topkg distrib
topkg publish
topkg opam pkg
topkg opam submit
# Create and release the other opam package based on the ditrib
topkg opam pkg --pkg-name mypkg-snd
topkg opam submit --pkg-name mypkg-snd
See topkg help release for more information about releasing
packages with topkg.
pkg.ml filesThis is a menagerie of pkg.ml with a description of what they
showcase. The examples are approximatively sorted by increasing
complexity.
In all these packages the readme, change log and license file are
automatically installed in the directory of the doc field and the
ocamlfind META file and opam file of the package are automatically installed
in the directory of the lib field.
hmap. The simplest you can get.fpath.fpath_top for toplevel support.astring namespaced by one module.astring_top).doc/ directory.fmt).fmt_top for toplevel support.fmt_tty
conditional on the presence of the opam base-unix package.fmt_cli conditional
on the presence of the opam cmdliner package.ptime.ptime_top for toplevel support.ptime_clock targeting regular OSes using
C stubs and installed in the os/ subdirectory of lib field along
with a private library archive ptime_clock_top for toplevel support.ptime_clock targeting
JavaScript installed in the jsoo/ subdirectory of lib field conditional
on the presence of the opam js_of_ocaml package.doc/ directory.uucp namespaced by a single module.src/ directory.support/ path to the paths to exclude
from the distribution.doc/ directory.carcass namespaced by a single module.carcass_cli.carcass.etc location in the software artefacts
with a pre-build hook.etc file hierarchy of the distribution.etc hierarchy of the distribution in the etc field
directly from the source tree (i.e. the files are not built).Topkg (META, topkg.opam, topkg-care.opam)
#mod_use directives), that's
only for using topkg on itself.lib
field.META install, a single one is installed for all opam packages
by the base package topkg. This leverages the if_exists ocamlfind
mecanism.topkg package installs the library archive topkg namespaced
by a single module.topkg-care package installs the library archive topkg-care
namespaced by a single module and the binaries topkg and
toy-github-topkg-delegate