ASDF 3
        
          ASDF is the de facto standard build facility for Common Lisp.
          Your Lisp implementation probably contains a copy of ASDF,
          which you can load using (require "asdf").
        
          ASDF 3 is the current successor to
          Daniel Barlow's ASDF (created on August 1st 2001) and
          François-René Rideau's ASDF 2 (released May 31st 2010).
          It was rewritten for improved portability, robustness, usability,
          extensibility, configurability, internal consistency,
          and the ability to deliver standalone executables,
          all while maintaining substantial backward compatibility.
          Its notable versions include pre-release 2.27 on February 1st 2013,
          first stable release 3.0.1 on May 16th 2013,
          major releases 3.1.2 on May 6th 2014,
          3.2.0 on January 10th 2017 and 3.3.0 on October 6th 2017.
          The latest release is 3.3.4, published on February 14th, 2020.
        
        
        What it is
        
          ASDF is what Common Lisp hackers use to build and load software.
          It is the successor of the Lisp DEFSYSTEM of yore.
          ASDF stands for Another System Definition Facility.
        
        ASDF 3 contains two parts: asdf/defsystem and uiop.
        
        
          - asdf/defsystem
- 
            is a tool to describe
              how Lisp source code is organized in systems,
              and how to build and load these systems.
              The build happens based on a plan in term of
              actions that depend on previous actions;
              the plan is computed from the structure of the systems.
             
              Typical actions consist in compiling a Lisp source file
              (unless already up to date)
              and loading the resulting compilation output
              (unless both already loaded and up to date).
              And you must typically compile and load
              files that define packages, macros, variables,
              before you may compile and load other files that use them.
             
              If you come from the C/C++ world, ASDF covers a bit of what
              each of make, autoconf, dlopen and
              libc do for C programs:
              it orchestrates the compilation and dependency management,
              handles some of the portability issues,
              dynamically finds and loads code,
              and offers some portable system access library
              (see uiop below for the latter).
              Except everything is different in Common Lisp,
              and ultimately much simpler overall,
              though it does require acquiring some basic concepts
              that do not exactly match those of the C and Unix world.
              Importantly, ASDF builds all software in the current Lisp image,
              as opposed to building software into separate processes.
             asdf/defsystem is the part that people usually refer to
              as ASDF,
              with uiop being only a supporting library,
              that happens to be distributed at the same time, by necessity.
             
- uiop
- 
            
              the Utilities for Implementation- and
              OS- Portability,
              formerly known as asdf/driver,
              is a Common Lisp portability library and runtime support system
              that helps you write Common Lisp software in a portable way.
             
              In addition to many general-purpose Lisp utilities,
              it notably provides portable abstractions to
              gloss over implementation quirks, support hot-upgrade of code,
              manipulate pathnames, create programs, use command-line arguments,
              access the environment, use the filesystem,
              call other programs and parse their output,
              compile Lisp code, muffle conditions, or configure Lisp software.
              See its
              README.md
              for an overview,
              and the documentation as extracted from its docstrings by
              Declt or
              HEΛP
              (NB: in HEΛP, you can, though it's not obvious,
              scroll the list of packages with a scrollbar
              on the right of the top-left pane,
              and then click on the package you're interested in
              to browse its symbols).
             
              uiop is distributed as part of ASDF:
              its source code is transcluded in
              the single-file asdf.lisp being distributed
              and the precompiled fasls provided by Lisp implementations.
              ASDF relies heavily on it
              for its portability layer and runtime support,
              particularly so as to handle pathnames and filesystem access.
              uiop is useful on its own
              and can also be compiled and distributed separately.
             
What it is not
        
          ASDF will not download missing software components for you.
          For that, you want
          Quicklisp,
          that builds upon ASDF, and is great for pulling and installing
          tarballs of packages you may depend upon.
          We also recommend
          clbuild,
          that now builds upon Quicklisp,
          as a great tool for pulling from version control
          packages you need to modify or want to contribute to.
          We recommend you should not use asdf-install
          anymore, as it is an older similar piece of software
          that is both unmaintained and obsolete.
        
          ASDF is also not a tool to build or run Common Lisp software
          from the Unix command-line.
          For that, you want cl-launch,
          buildapp, or
          roswell.
        
          If you're unsatisfied with ASDF,
          beside helping with our
          TODO list,
          you might be interested in other build systems for Common-Lisp:
          
            - Google's deterministic and scalable build system
              Bazel,
              for which Lisp support is available:
              bazelisp.
            
- Alastair Bridgewater's small and simple one-package-per-file
              quick-build
              (also reimplemented as the ASDF extension
              asdf-package-system, now part of ASDF 3;
              similar to faslpath below).
            
- François-René Rideau's
              XCVB
              (building object and image files deterministically
              and in parallel, but
              not actively maintained and bitrotten since 2012;
              a hypothetical ASDF 4 could conceivably be evolved to support
              these features thanks to the groundwork laid by ASDF 3;
              or you could use Bazel).
            
- Drew McDermott's
              YTools
              (the polar opposite of XCVB, trying to maintain coherence
              of the current Lisp image at a fine grain).
            
- Dmitriy Ivanov's
              ASDlite
              (a somewhat improved incompatible variant of ASDF 1,
              much less featureful, robust or portable than ASDF 3),
            
- Mark Kantrowitz's
              mk-defsystem
              (free software successor of the old proprietary DEFSYSTEM's
              and predecessor of ASDF, obsolete),
            
- Sean Ross's
              mudballs
              (an attempt at making things cleaner than in ASDF 2, aborted),
            
- Peter von Etter's
              faslpath
              (a much simpler system establishing a mapping
              between packages and files, abandoned but
              see asdf-package-system and quick-build above),
            
- Alexander Kahl's
              evol
              (a reimplementation in Lisp of the GNU autotools stack,
              abandoned).
            
          There are probably more. However, none of these systems seems
          to ever have had the traction of ASDF, probably because
          none was technically superior and/or portable enough (if at all)
          to compensate for the first mover advantage.
        
        
        Supported Implementations
        
          ASDF 3 now supports all CL implementations
          that seem to have any current user base, and then some.
          But ASDF does not magically turn
          broken implementations into working ones,
          and some ASDF or UIOP features may not work
          on less-maintained implementations that do not support them
          (see below).
        
          Most implementations provide ASDF as a module,
          and you can simply (require "asdf").
          (All of them but CLISP also accept
          :asdf, "ASDF" or 'asdf as an argument.)
          All these implementations provide ASDF 3.1 or later in their latest version,
          but your software distribution might have an older version.
        
          As for remaining implementations,
          they are obsolete and/or mostly unmaintained;
          ASDF was made to run with each of them at some point,
          but some hacking is probably required
          to make the latest ASDF work well
          with the latest release of these implementations:
          
- 
              CLISP is generally well-tested with ASDF,
              though it has a few minor bugs.
              The implementation has received only
              minimal maintenance since 2010,
              and the last official release doesn't ship with ASDF,
              or often has antique version of ASDF tucked on it.
              However, ASDF has been recently updated
              in its source control system,
              and there is hope of a new release some day soon.
              If needs be, you can replace CLISP's provided ASDF
              with a newer one, or use an upgrade on top of that.
            
- 
              CormanLisp was recently open-sourced.
              Its bundled ASDF has not yet been updated from 1.x;
              ASDF 3 should work fine with it, but
              several features were disabled
              because CormanLisp was insufficiently compliant with the CLHS,
              and requires some work in this regard.
              Ask the new CormanLisp maintainers for updates.
            
- 
              ECL is generally well-tested with ASDF, but
              its bytecode compiler doesn't support the bundle operations, and
              support for Windows seems to be less stable.
              For instance, as of January 2017,
              cl:requireandext:system(and thusuiop:run-program)
              seem not to be working correctly on Windows.
- 
              GCL is somewhat maintained but
              its maintainer doesn't seem to care about ASDF,
              and hasn't replied for years to requests for bug fixes or
              for providing ASDF via (require "asdf")
            
- 
              Genera was never open-source and never bundled ASDF,
              but should otherwise just work with a recent ASDF 3,
              if you somehow have a license and a working version.
              There are rumors of people doing active development with it
              and having minor patches to improve ASDF on it.
            
- 
              MCL similarly was open-sourced, but never bundled ASDF;
              ASDF 3 should work just fine with it,
              but Rosetta is not supported in the latest versions of MacOS X,
              so a lot of work is required to make something out of it
              — at which point, you might just use CCL.
            
- 
              Mocl has its own heavily modified variant of ASDF2, and
              is the only implementation not currently supported by ASDF3.
              To make it work with ASDF 3 would require ASDF to be taught about
              natively supporting cross-compilation.
            
- 
              SCL was seemingly abandoned and never open-sourced.
              It never bundled ASDF, but otherwise
              should just work with a recent ASDF 3,
              if you somehow have a license and a working version.
            
- 
              XCL is now an abandoned experiment.
              It provides some old ASDF 2;
              but you can replace it with ASDF 3, which works well with it,
              inasmuch as anything works at all with XCL.
          
          |  | Provide ASDF 3.1 or later | No ASDF | Unmaintained | 
|---|
          | Free | ABCL,
              CCL,
              Clasp,
              CLISP,
              CMUCL,
              ECL,
              Mezzano,
              MKCL,
              SBCL | CormanLisp,
              GCL,
              MCL | XCL | 
|---|
          | Proprietary | Allegro,
              LispWorks |  | Genera,
              mocl,
              SCL | 
|---|
        
        
          To deal with an implementation that does not yet provide ASDF 3.1 or later,
          we provide
          a script
          that will install the ASDF from your git checkout
          to where your implementation goes looking for it
          when you (require "asdf").
        
          Note that upgrading from an old version of ASDF 2 or earlier
          is possible, but quite complex to do right in a robust way,
          and we do not recommend it.
          Also note that mocl only supports
          a heavily modified variant of ASDF 2,
          and will require robust cross-compilation support
          to be added to ASDF
          before it is actually supported.
        
        
        
          If there is an old or new implementation that we are missing,
          it shouldn't be hard to adapt ASDF to support it.
          Ask us!
        
        
        Examples
        Download any of the many packages available through
          Quicklisp
          to see as many examples.
        
        Documentation
        You can read our manual:
        
        
          The first few sections,
          Loading ASDF,
          Configuring ASDF
          and Using ASDF
          will get you started as a simple user.
        
          If you want to define your own systems, further read the section
          Defining systems with defsystem.
        
          There is now also a
          Best Practices
          document explaining recommended usage patterns when writing .asd files,
          and detailing common pitfalls or deprecated practices to avoid.
        
          About the latest developments in ASDF 3.2 and ASDF 3.3, see our demo
          Delivering Common Lisp Applications with ASDF 3.3
          (2-page PDF,
          slides,
          git).
          Regarding the internal design of ASDF in general,
          and the work we did on ASDF 3,
          see the extended version (26 pages) of our paper
          ASDF 3, or Why Lisp is Now an Acceptable Scripting Language
          (PDF,
          git).
          The shorter version (8 pages), presented at
          ELS 2014,
          focuses on ASDF 3 and misses historical and technical information
          (PDF,
          HTML).
          Regarding ASDF 3, see also the slides of the
          ASDF 3 tutorial presented at ELS 2013,
          and for an introduction to the source code, this video:
          ASDF 3.1 walkthrough.
          For details about our previous work on ASDF 2,
          see our paper presented at
          ILC 2010,
          Evolving ASDF: More Cooperation, Less Coordination
          (git).
        
        
          Finally, while the manual covers all the basics,
          some advanced or new features remain underdocumented.
          Please contact our mailing-list (see below)
          regarding any feature that isn't well-documented enough.
        
        
          Until we write more documentation on the further innovations of ASDF,
          the documentation strings,
          the source code,
          the changelog
          and the git log
          are unfortunately your best chances
          for discovering the available functionality.
        
        
        Getting it
        Though they may lag behind the version here,
          ASDF comes bundled with most Lisps.
          To get the greatest and latest, you can:
        
        
        
        Extensions
        Known extensions to ASDF include:
        
          - 
            
            asdf-dependency-grovel,
            to compute the actual dependencies in a big ASDF system.
- asdf-encodings,
            to compile Lisp source files with character encodings other than UTF-8.
- asdf-finalizers,
            to allow macros to include code to be evaluated
            at the end of a file being compiled.
- asdf-flv,
            to bind file-local variables around the compilation of some files.
- asdf-system-connections,
            lets you specify systems that are automatically loaded when
            two other systems are loaded, to connect them.
- cffi,
            lets you interface between functions and datastructures written in C
            and functions written in Lisp,
            including support for
            automatically detecting constants from C macros,
            linking to dynamic (and now also static) libraries, and
            writing your own wrapper code in C.
- poiu,
            to compile a system in parallel on a multiprocessor machine.
Former extensions, now superseded, include:
        
          - asdf-binary-locations
            used to allow one to redirect where ASDF 1 created its output files,
            so they don't clash between implementations
            and don't pollute source directories.
            It is superseded by asdf/defsystem's builtin
            asdf-output-translations mechanism;
            a limited compatibility mode is available to easily convert
            your former ABL configuration into an AOT configuration.
            common-lisp-controller and cl-launch
            used to provide similar mechanisms,
            and have also been superseded by asdf-output-translations
            (built into ASDF 2 and later).
          
- asdf-bundle, née asdf-ecl,
            allowed you to create a single-file bundle out of a system,
            for easier delivery.
            It is now a builtin part of asdf/defsystem,
            and allows users to deliver a single FASL for a system,
            a standalone executable program (on supported implementations),
            or an image containing your system precompiled.
          
- asdf-condition-control,
            initially part of XCVB's xcvb-driver,
            allowed you to muffle uninteresting conditions during compilation.
            Is now superseded by equivalent functionality in uiop.
          
- asdf-contrib,
            an empty package that used to collect dependencies on other systems
            in the list above and below.
- asdf-package-system,
            to compile Lisp source files with one package per file
            that also determines dependencies, in the style of
            quick-build or
            faslpath
            (this functionality is built into recent versions
            of ASDF 3.1 and later,
            but this package exists for backward compatibility
            with earlier versions of ASDF 3;
            search the manual for package-inferred-system).
          
- asdf-utils was a collection of utilities
            that originated with ASDF.
            It is now superseded by uiop, aka asdf/driver,
            which is part of ASDF,
            and exports its functionality
            in its own package uiop.
          
Contributing
        Join our mailing list, check the code out from git,
          send questions, ideas and patches!
        
        
        Reporting Bugs
        To report bugs, you can use our
          common-lisp.net project.
          If you're unsure about the bug or want to discuss how to fix it,
          you can send email to the project mailing-list below.
        
        
          Note that the most valuable thing you can send this way
          are test cases,
          if possible as .script files
          readily runnable by our test system.
          If you're courageous, send us merge requests on
          gitlab.
        
        
          While bug fixes are useful,
          they are not usually as valuable as test cases:
          small easy fixes will be obvious from the test case,
          and large fixes written by someone who isn't
          either a maintainer or working tightly with one
          will probably not be correct and not fit the codebase:
          any modification at one point is likely to have repercussions
          at other unobvious places in the codebase,
          for the code to be correct in a wider variety of scenarios
          than casual developers usually think about.
          Now, if you're willing to become a maintainer,
          you're welcome to join the team!
        
        
          NB: Previously, we had done bug-tracking on
          launchpad.net,
          but we are now consolidating project management on
          common-lisp.net.
          If you are interested in hacking on ASDF, you may look at the bugs on launchpad
          for more work to do (if only to migrate the bugs to gitlab).
        
        
        Mailing Lists
        
          - asdf-devel
            A list for questions, suggestions, bug reports, patches, and so on.
            It's for everyone and everything. Please join the conversation!
          asdf-devel
        mailman site to subscribe
          
- asdf-announce
            A low-volume mailing-list for announcements only,
            mostly regarding new releases.
            Posting is restricted to project administrators
            and to important notices.
            Please subscribe to it
            if you're a Lisp implementation or distribution vendor,
            who needs to know when to upgrade the ASDF you distribute,
            but are otherwise not interested in day to day design and
            development.
            asdf-announce mailman site to subscribe
        
Contributing
        Join our mailing list, check the code out from git,
          send questions, ideas and patches!
        
        
        What is happening
        For a detailed description of changes see our Changelog
        
        
          - February 2020
-  Release of 3.3.4: fourth bugfix release for the 3.3
          release series.
- March 2019
- Release of 3.3.3: third bugfix release for the 3.3 release series.
- May 2018
- Release of 3.3.2: second bugfix release for the 3.3 release series.
- November 2017
- Release of 3.3.1: bugfix release for 3.3.0 addressing
            a backwards-incompatibility issue with timestamp computations,
            and other minor breakage.
- October 2017
- Release of 3.3.0, with substantial revision to the build plan
            to correct handle multiple phases of loading, due to e.g.
            DEFSYSTEM-DEPENDS-ONdependencies.
- April 2017
- Release of 3.2.1, with many small bugfixes and cleanups.
            Presentation at ELS 2017 about ASDF 3.3.
          
- January 2017
- Release of 3.2.0, a release containing many notable improvements,
            such as a new portable uiop:launch-program facility for
            spawning asynchronous subprocesses
            (with many thanks to Elias Pipping),
            a uiop:with-deprecation facility to handle
            progressive deprecation of functions,
            a cleanup and tightening of the internal dependency model
            (you are now required to use make-operation
            to instantiate an operation class; also you'll be WARNed if your
            .asd file contains improperly named secondary systems),
            a systematic pass of adding documentation to all functions,
            many fixes to small bugs and portability issues
            across all underlying platforms and operating systems,
            an improved test suite,
            and the removal of some long deprecated functionality.
- March 2016
- Release of 3.1.7, another bug fix release for the 3.1.x series.
- October 2015
- Although we had hoped that ASDF 3.1.5 would be the final release
        in the ASDF 3.1 series, a number of bug reports led us to prepare
        release 3.1.6.  Support for Windows continues to improve, and we wished
        to release a number of bug fixes, and support the recent Allegro Common
        Lisp 10.0 release.
- July 2015
- An extensive bout of bug-fixing, notably on Windows, leads to
        release of ASDF 3.1.5 on 21 July 2015. XDG handling has been improved to
        be more compliant with the standard. Preliminary support for
        immutable systems has been added.
- May 2015
- With the LispWorks 7.0 release, all actively maintained CL implementations
        are now providing ASDF 3.0 or later, and
        support for older variants is now officially dropped.
- October 2014
- More bug fixing leads to release of 3.1.4 on 10 October 2014.
          There should be no incompatibilities.
          See the Changelog for more details.
- August 2014
- The ASDF mailing lists have been reestablished, in particular
        asdf-announce, which should allow CL implementers better access to only
        the information they want about ASDF development.
- May 2014 to July 2014
- ASDF bug fixing from 3.1.2 leads to release of 3.1.3, a major bug
        fix release.  We strongly urge implementors that have shipped with 3.1.2
        to upgrade to 3.1.3. There should be no incompatibilities, and some
        very important bug fixes are provided. See the Changelog for more details.
- July 2013 to May 2014
- François-René Rideau has resigned as maintainer
            but remained an active developer.
            Robert P. Goldman is interim maintainer until someone more gifted,
            charming, dedicated, and better-looking can be secured to fill the role.
            ASDF 3.0.2 was released in July 2013, 3.0.3 in October 2013, and 3.1.2 in May 2014.
            In addition to significant improvements and bug fixes,
            notably better Windows support,
            ASDF 3.1.2 notably sports the package-inferred-system extension.
          
- November 2012 to June 2013
- 
            François-René Rideau completely rewrites ASDF
            and publishes ASDF 3, pre-released as 2.27 in February 2013,
            and released as 3.0.1 in May 2013.
            It now includes both the traditional asdf/defsystem
            and a formalized portability library uiop (née asdf/driver).
            asdf/defsystem is a backward-compatible reimplementation of ASDF
            with correct timestamp propagation based on a consistent dependency model,
            and featuring support for bundle output, deferred warnings check, and more.
            uiop provides many abstractions to write portable Common Lisp programs.
            Last version: 3.0.1.
          
- December 2009 to October 2012
- François-René Rideau is de facto maintainer,
            with notable contributions from Robert P. Goldman, but also
            Juanjo Garcia-Ripoll and James Anderson.
            ASDF 2.000 is released in May 2010
            with many clean-ups, better configurability, some new features,
            and updated documentation.
            The ASDF 2 series culminates with ASDF 2.26 in October 2012,
            which in addition to many bug fixes and small features
            includes support for file encodings, around-compile and compile-check hooks.
            Last version: 2.26.
          
- May 2006 to November 2009
- Gary King is de facto maintainer,
            with notable contributions from
            Robert P. Goldman, Nikodemus Siivola, Christophe Rhodes, Daniel Herring.
            Many small features and bug fixes,
            making the project more maintainable,
            moving to using git and common-lisp.net.
            Last version: 1.369.
          
- May 2004 to April 2006
- Christophe Rhodes is de facto maintainer,
            with notable contributions from
            Nikodemus Siivola, Peter Van Eynde, Edi Weitz, Kevin Rosenberg.
            The system made slightly more robust, a few more features.
            Last version: 1.97.
          
- August 2001 to May 2004
- Created then developed by Daniel Barlow, with notable contributions from
            Christophe Rhodes, Kevin Rosenberg, Edi Weitz, Rahul Jain.
            Last version: 1.85.