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Historic Overview of ASDF

Build system

transform source (for humans) into binary (for machine)

a bit like make for C

enable division of labor

divide the source into separate components

multiple people can collaborate, each making changes to a few components

people in different teams, in same team, in same cranium.

system: CL name for top-level unit of software management

In other languages they are called: library, package, module, bean, egg, class, archive…


Configuration: find where is each file needed

Dependencies: build things in correct order

Incrementality: re-build iff changed

No build system

What a manual load file might look like, this-software-loader.lisp

(load #p"/path/to/library1.lisp")
(defparameter *library2-directory* #p"/path/to/library2/")
(load (merge-pathnames #p"source/loader.lisp"
(setf (logical-pathname-translations "LIBRARY3")
      `(("**;*.*.*" #p"/path/to/library3/*.*")))
(load #p"LIBRARY3:load-library3.lisp")
(load (compile-file
       (merge-pathnames "file1.lisp"
(load (compile-file
       (merge-pathnames "file2.lisp"
(load (compile-file
       (merge-pathnames "file3.lisp"

Previous example with ASDF

File this-software.asd

(defsystem this-software
   :depends-on (library1 library2 library3)
   ((:file "file1")
    (:file "file2" :depends-on "file1")
    (:file "file3" :depends-on "file1")))

Solved by ASDF

Can find libraries w/o specific configuration

Can find files inside library w/o extra configuration

Configuration is done separately and uniformly

dependencies: finer information is captured

incrementality: only build what’s needed

more: portability, extensibility, etc.

ASDF descends from DEFSYSTEM

build system: compile source files

specialized: oriented toward CL software

not geared for arbitrary tasks with dependencies

in image: also load software

totally unlike either make

maintain long-lived system state

declarative: describe system dependencies

not imperative instructions on how to build

got more declarative as DEFSYSTEM grew older

Lisp build system history

196x: Manual load scripts

197x: Lisp Machine DEFSYSTEM

Chine Nual: components and manual rules

198x: kmp’s MIT AI Memo 801, rer’s MIT AI TR 874.

198x: Symbolics SCT

very elaborate, proprietary

1991: MK-DEFSYSTEM. 3.6i: 218kB.

free, portable, but complex, feature poor, not extensible

199x: also defsystem of Allegro, LispWorks

proprietary, quality between MK-DEFSYSTEM and SCT.

2002: ASDF, by Dan Barlow et al. 1.85: 38kB. 1.369: 77kB.

configurable, extensible, semi-portable.

2010: ASDF2, by Faré et al. 2.000: 138kB. 2.26: 198kB.

robust, portable, usable, upgradable

See “Evolving ASDF: More Cooperation, Less Coordination”

2013: ASDF 3, by Faré. 2.27: 409kB. 3.0.1: 459kB.

Fix 30-year old bug by making design coherent, new features

Future: ASDF 4? quick-build? XCVB? Racket?

ASDF Features

A simpler, better replacement for MK-DEFSYSTEM

Use CLOS, don’t support obsolete platforms

focus on SBCL and Unix

ported to a handful other implementations

Inter-system configuration: find systems though *central-registry*

No need to edit a file for every system any more!

Typically, “symlink farms” – but Unix specific

Intra-system configuration: none needed, use TRUENAME

Brilliant key idea establishes ASDF dominance

Extensibility: use of CLOS to model dependencies

Example in SB-GROVEL

ASDF success

Its configuration mechanism was a brilliant innovation

Before you laugh, compare to autotools, pkgconfig, etc.

Extensible CLOS model also innovative, but not fully understood

Not by me until I rewrote it, not by Dan Barlow himself.

In many ways, a discovery, not an intentional design.

Became de facto standard

quicklisp: over 700 libraries

Now a key piece of community infrastructure

Therefore cursed with backward-compatibility

if it’s not backward…

ASDF 1 issues

Many shortcomings:

Not very portable

Pathnames horror

A lot of bugs outside the common case

No standard way to load it

Yet development stalled:

Users wait for new version before to rely on features / bug fixes

Implementers wait for users to demand new version before to change and break compatibility

Some distributions pre-package CL with ASDF pre-loaded, others don’t

If an old one is pre-loaded, it’s too late to upgrade with a version with bugs fixed

ASDF 2 Features

Hot-upgradable: reverse incentive so development can happen

Portable: 15 implementations, 4 OSes

Robust: Massive bug fixes

Massive cleanup of internals. Pathname hell. Corner cases.

Faster: Don’t use lists when inappropriate

Can now scale to thousands of files

Configurable: by end-users, not just developers

Domain-Specific Language for better configuration

Modular update of configuration

Usable: a whole lot of small missing features

(asdf:load-system :foo) instead of (asdf:operate 'asdf:load-op 'foo)

load-system test-system require-system

:defsystem-depends-on :force-not :encodings :around-compile :compile-check

ASDF 3 Features

Complete refactoring, fixed deep conceptual bugs.

Deliver your system(s)

as single fasl (fasl-op)

as single lisp source file (concatenate-source-op)

as an executable program (program-op), with runtime hooks

Portability: new library UIOP, includes RUN-PROGRAM

Condition Control: muffle warnings, keep deferred warnings

naming: multiple systems in foo.asd: foo/bar, foo/baz

more: :if-feature build-op force precompiled-system

How to use ASDF

What ASDF does

Compile and load Lisp code in current image

Locates software based on configuration

Provide extensible object model to developers

What ASDF does not

Download code (but quicklisp does)

Solve version hell (only checks as specified)

Build non-Lisp stuff (awkward)

Example minimal ASDF session

(require :asdf)
(asdf:load-system :inferior-shell)
(in-package :inferior-shell)
(run `(pipe (echo ,(* 90 137)) (tr "1032" "HOLE")))

;; More:
(run `(grep "Mem" "/proc/meminfo") :output :lines)
(asdf:test-system :inferior-shell)

Using ASDF, the safe way

;; CLISP alone won't accept :asdf
(require "asdf")

;; active implementations provide ASDF2 or later
#-asdf2 (error "You lose")

;; force ASDF2 to upgrade to your installed ASDF3
(asdf:load-system :asdf)

Using ASDF, the hard way

see slime/contrib/swank-asdf.lisp

tries hard when the implementation doesn’t provide ASDF.

Even harder: see lisp/setup.lisp from quux (to be published)

configure asdf, twice, to work around cases of unsmooth upgrade.

Using CL-Launch from command-line

cl-launch -s this-software -i '(this-software:main)' \
	-- arg1 arg2

Using CL-Launch from script

":" ; DIR="$(cd $(basename "$0");pwd)" #|
exec cl-launch -l ccl -S "$DIR//:" -i "$0" -- "$@"
exit |#
(some lisp code)

How to configure ASDF

How to configure ASDF

Source Registry

Output Translations

Optimization, verbosity, etc.

Default Installation Paths

No need to configure if you use defaults




FASLs under ~/.cache/common-lisp/

Source Registry, via config file


  (:directory "/myapp/src")
  (:tree "/home/tunes/cl")

Unlike ASDF 1, forgiving of no final /

Source Registry, via modular config file


(:directory "/myapp/src")

Source Registry, via environment

export CL_SOURCE_REGISTRY=/myapp/src/:/home/tunes/cl//:

Source Registry, via Lisp evaluation

     (:directory ,appdir)
     (:tree ,librootdir)

Old Style central registry

(pushnew #p"/myapp/src/" asdf:*central-registry* :test 'equal)

Catch: ASDF 1 was unforgiving if you forgot the trailing /

Magic: argument actually evaluated.

ASDF 2 has asdf::getenv, now uiop:getenv

No portable place to do it with ASDF 1.

e.g. ~/.sbclrc on SBCL.

source-registry can be configured in a decentralized way

Each can specify what he knows,

none need specify what he doesn’t

Output Translations

Where is the fasl for foo.lisp ?

Multiple implementations and variants may use the same name

Allegro 9.0 SMP vs Allegro 9.0 normal

SBCL 1.1.0 vs SBCL 1.1.8

SBCL 1.1.0 x86 vs SBCL 1.1.8 x86_64

Many ASDF1 extensions to move FASLs away, but hard to configure

No consensus solution on where to put things




Output Translations, via config file


  (t (,cache-root :implementation))

Output Translations, via modular config file



("/myapp/src/" ("/var/clcache" :implementation "myapp/src"))

Output Translations

export ASDF_OUTPUT_TRANSLATIONS=/:/some/cache/dir/:

     (t (,cache-root :implementation))

Output Translations, $PWD/sbcl-1.2-x86/foo.fasl

    (t (:root :**/ :implementation :*.*.*))

Using quicklisp and clbuild

(load "quicklisp/setup.lisp") does it all

I’m not sure about clbuild — use the source-registry

How do I find a library?

Just use quicklisp

Google it, search Cliki,

Ask the community, e.g. #lisp

Where do I download it?

Just use quicklisp

To some place in your source-registry

zero conf: ~/.local/share/common-lisp/source/

Build script

Optimizations: (declaim (optimize ...)

Parameters: (setf *compile-verbose* nil)

easy build script: sbcl --load build.lisp

For portability, use cl-launch as above

How to define a simple ASDF system

Creating Basic ASDF Systems


(asdf:defsystem foo 
  ((:file "foo")))

Depending on other systems


(defsystem foo
  :depends-on (:alexandria :cl-ppcre)
  ((:file "foo")))

Multiple files


(defsystem foo ...
  ((:file "pkgdcl")
   (:file "foo" :depends-on ("pkgdcl"))
   (:file "bar" :depends-on ("pkgdcl"))))

Typical small system


(defsystem foo ...
  ((:file "pkgdcl")
   (:file "specials" :depends-on ("pkgdcl"))
   (:file "macros" :depends-on ("pkgdcl"))
   (:file "utils" :depends-on ("macros"))
   (:file "runtime" :depends-on ("specials" "macros"))
   (:file "main" :depends-on ("specials" "macros"))))

Bigger system: divided in modules

(defsystem foo ...
  ((:module "base"
      :components ...)
   (:module "runtime"
      :depends-on ("base")
      :components ...)

Logical Modules, same directory

(defsystem foo ...
  ((:module "base"
      :pathname ""
      :components ...)

Pathname override

(:file "foo/bar")
(:file "foo" :pathname "../sibling-dir/foo")
(:file "foo" :pathname #p"../sibling-dir/foo.LiSP")

Sibling directories

(:file "../sibling-dir/foo")
(:module "../sibling-dir/foo")
(:file "foo" :pathname "../sibling-dir/foo")
(:file "foo" :pathname #p"../sibling-dir/foo.LiSP")

Punting on fine-grained dependencies

(defsystem foo
  :serial t
  ((:file "pkgdcl")
   (:file "main")))

Serial Dependencies

Scope of :serial t is the current module or system

not its submodules or systems.

You can easily nest serial / parallel dependencies

Explicit Dependencies

:depends-on ("foo" "bar/baz" "quux")

Good Style

No in-package

Only defsystem forms for foo, foo/bar

Any classes, methods from :defsystem-depends-on

No other methods, no side-effect, no pushing features

Other files in a project


Using quickproject

Automatically create the skeleton

How (not) to map packages and systems

Distinct namespaces

find-package vs find-system

A system may or may not define a package of same name

Strategy 1: one package per system

The traditional way

system foo, package foo

system cl-foo, package foo (yuck)

system cl-foo, package cl-foo

file pkgdcl.lisp or package.lisp

Strategy 1b: one package per subsystem

Whether you subsystem is a second system or a module

system foo, system foo/bar

see iolib

Strategy 2: interface vs implementation package

package foo, package foo-impl

same system foo, or

two systems foo/interface and foo/implementation

See cl-protobufs

Strategy 3: one package per file

More discipline, reduces mess

dependencies implicit from defpackage

See source code of ASDF 3 itself

faslpath, quick-build use it for dependencies!

if you :use or :import-from a package, load it first

uiop:define-package vs defpackage

Part of UIOP, new in ASDF 3

Works well with hot-upgrade

Automation common patterns:

(:mix "foo" "bar")

(:reexport "foo" "bar")

.asd file syntax

ASDF 3: now read in UTF-8 encoding, not :default

ASDF 3: Now read in package ASDF-USER, not a temporary package

Compatibility: NOT binding *readtable* and *print-pprint-dispatch*

Deprecated: arbitrary code in .asd file

Recommended: only calls to defsystem, use :defsystem-depends-on


Issue: avoid name conflict issues between .asd files

Old ASDF 1 & 2 read each file in its own temporary package

ASDF 3 now all reads them in a common package ASDF-USER


Not UIOP due to conflict with RUN-PROGRAM in SB-GROVEL

ASDF is not the right place for this “innovation”

If you’re CL programmer, you know your package discipline

If you don’t know your package discipline, you’re screwed anyway

Best package practice

No need for (in-package :asdf) in your .asd file

Read in shared namespace ASDF-USER — usual discipline applies

If you bind new symbols, use DEFPACKAGE first.


How to use advanced ASDF features

Using Extensions: CFFI Grovel

(defsystem foo
  :defsystem-depends-on (:cffi-grovel)
  :depends-on (:cffi)
  ((:cffi-grovel-file "c-prototypes")
   (:file "lisp-code" :depends-on ("c-prototypes"))))

Character encoding, since 2.21

(defsystem foo
  :encoding :latin1
  ((:file "pkgdcl" :encoding :utf-8)
   (:module "russian" :encoding :iso-8859-5
      :components ((:file "bar" :encoding :koi8-r) ...))))

*default-encoding* is now :utf-8 since 2.31

a boon for most programs, work predictably

breaks a handful on unmaintained packages in quicklisp

Finalizers, since 2.23

(defsystem :asdf-finalizers-test
  :defsystem-depends-on (:asdf-finalizers)
  :depends-on (:list-of :fare-utils :hu.dwim.stefil)
  :components ((:file "asdf-finalizers-test")))


(defun foo (l)
  (check-type l (list-of string)))



(asdf:load-system :poiu)

(asdf:load-system :this-software)

Compile in a fork, load in current image.

Replay compilation errors in current image

antifuchs 2007-2008: build ASDF systems in parallel

fare 2009-2013: robust, portable, integrated to ASDF

Deterministic by default given initial state

Faster option: more parallelism

Can fork on SBCL, Single-threaded CCL, CLISP, ACL

Graceful fallback if no forking.

Handle deferred warnings

How the ASDF object model works

Components, Operations, Actions

COMPONENT’s describe your source code


OPERATION’s are stages of processing to perform on components


An ACTION is a pair of an OPERATION and a COMPONENT

e.g. (cons (find-operation () 'load-op) (find-component "this-software" "file1"))

The dependency graph is a direct acyclic graph of ACTION’s

It is not a graph of components that depend on each other.

Plan first, then perform


Factoring out PERFORM-PLAN was a recent change before ASDF 3.

TRAVERSE walks the dependency graph and returns a plan

Traditionally, a LIST of actions to perform in order

Can be overridden. POIU returns a representation of the complete graph.

PERFORM-PLAN walks the plan calling PERFORM-WITH-RESTARTS on each ACTION

PERFORM-WITH-RESTARTS sets up proper restarts and calls PERFORM

The graph is computed by COMPONENT-DEPENDS-ON

Misnamed: actions, not components, have dependencies.

Arguments: an operation designator, component designator

e.g. (COMPONENT-DEPENDS-ON 'LOAD-OP '("this-software" "file2"))

CLOS: OO multi-dispatch on two arguments!

Return a list of lists of operation designator and component designators

e.g. ((#<LOAD-OP> #<CL-SOURCE-FILE "this-software" "file1">))

CLOS: don’t forget to append the (call-next-method)

we could have used the APPEND method combinator, but are not,

for historical backward compatibility reasons

CLOS: inherit from mixins to achieve desired effects

CLOS makes things very modular. Big win!

Component classes

Usual classes


Usual mixins

parent-component, child-component

Typical component tree


Operation classes

compile-op, load-op


new in ASDF 3: prepare-op, prepare-source-op

Also new in ASDF3, bundle-op and friends:

fasl-op, load-fasl-op

monolithic-fasl-op, monolithic-load-fasl-op

concatenate-source-op, load-concatenated-source-op


Typical operations mixins (ASDF 3):





Action Files

OUTPUT-FILES: output-translations in an :AROUND method


An action is NEEDED-IN-IMAGE-P iff its OUTPUT-FILES is nil

Otherwise, it need not be PERFORM‘ed again in current image if files up to date

Important notion implicit in ASDF 1&2, introduced by POIU

ASDF 3’s TRAVERSE may visit an action twice

once with NEEDED-IN-IMAGE-P NIL and oncep with it T

The bug that launched ASDF 3

ASDF 2.26 was stable

ASDF had been completely rewritten since ASDF 1

Now made portable, robust, usable, etc.

Everything had been touched except trivial things

But core dependency traversal algorithm unchanged

To fix bugs, refactored out of spaghetti code, but

functionally equivalent, modulo bug fixes

TRAVERSE was the holy relic passed by Dan Barlow

I didn’t grok the design, it felt slightly wrong.

Couldn’t change anything by fear of backward compatibility

Remained only one bug to procrastinate on

All other bugs were wishlist items made difficult by current design

Failure to propagate dependency changes

lp#479522 changes fail to trigger a rebuild across systems

explicitly disabled in TRAVERSE

In olden days, some have argued for the former bug as a “feature”

It was only a crock to work around lack of :force-not

When you enable the obvious fix, it only works in current session

system2 depends-on system1

in one session, change system1, recompile it

in another session, compile system2 that didn’t change

ASDF 1 and 2 fail to recompile system2

Not just between systems!

More common failure mode:

Use a stateful macro, such as DEFPACKAGE’s :use

have file1 define the macro, file2 use it

modify file1, file2 is not recompiled

Other common failure mode:

have file1, file2, file3 with serial dependencies

file1 has changed, file3 hasn’t

file2 completely breaks the build

you fix file2, and restart the build

ASDF 2 fails to recompile file3

Decades Old Dependency Bugs

Cause: ASDF only checked timestamp for files of action

Doesn’t even try to propagate timestamp from dependencies! lp#1087609

Need-to-recompile may be propagated only from current session

Bug present in 1991 MK-DEFSYSTEM and the original 197X DEFSYSTEM

Optional fix in Symbolics, Allegro, LispWorks defsystem

offer a different kind of dependencies than the default

broken by default (backward compatibility?)

not a complete fix in LispWorks

Fixing the bug requires a complete rewrite of ASDF’s TRAVERSE

Twice. Because then you find you need a correct dependency model

along which to correctly propagate timestamps.

Why never reported before?

Usually not THAT big an issue

Most Lispers hack on one small system at once.

Usually you interactively use the CONTINUE restart after fixing bug.

When you change file1, you often need to change file3, too, anyway.

In doubt, you :force a build from clean or erase all the fasls.

Now given in large systems built in batch with stateful macros… Ouch.

false positives and negatives waste time in building and testing

uncontroled non-determinism in testing is bad

Not your typical Lisp development style!

Live Programming vs Dead Programs

Live Programming: code is mutable

Short feedback “OODA” loop. Low overhead (meta)computing.

Dead Programs: code is immutable

Easier to analyze before it’s run. Too late to debug afterwards.

Both matter for the same reason:

programmer interaction is a scarce resource

On-line, adj.: The idea that a human being should always be accessible to a computer.

Computing systems of the future should support both in synergy.

Live style to metaprogram dead style programs.

Zombie programs that resurrect on-demand.

ASDF 3: traversing dependencies correctly

Solution: road to ASDF3

Propagate timestamps

This in turn necessitates a complete graph representation

Introduce prepare-op

This means refactoring downward propagation away from TRAVERSE

Refactor traverse and the operation classes

This means reorganizing the source code

Split the code into files so it makes sense

Implement monolithic-concatenate-source-op

Merge in and fix the asdf-bundle infrastructure

Recursively use new traverse to walk the partial plan for an action

It now makes sense to have a separate portability layer

Implement UIOP, spend time making it a quality library

Many cleanups and new features are now unlocked

Spend a lot of time implementing them robustly

Some new features are oh so slightly backward incompatible

Spend a lot of time fighting the community, and losing


introduced to fix a conceptual bug in the ASDF object model.

“load the dependencies of a component and its parents”

explicitly depends-on‘ed by LOAD-OP and COMPILE-OP

Propagates upward in the component hierarchy, not downward

TRAVERSE special cases such dependencies no more

TRAVERSE was gutted out

Not only bug fixes, but much simpler, sensible semantics

Now propagating timestamps along a graph and that only

Refactored into reusable higher-order functions and objects

The object model now actually makes sense, and can be extended

No more implicit descending into children components

Inherit from downward-operation for such propagation

methods take a plan object, NIL for actual action

Informed by interface-passing-style and experience with POIU

Was necessary to get BUNDLE-OP right portably

Many many thanks to antifuch’s POIU

COMPONENT-DEPENDS-ON is now more powerful

can express dependencies on arbitrary operation objects

Supported: depend not just on siblings

Supported: express arbitrary build graphs

Deprecated: operations with different options

Deprecated: depending on component in other system


It used to specify some dependencies that were skipped

if no re-build was triggered based on local timestamps;

ASDF 1 didn’t let the users control it,

ASDF 2 only let you control it since 2.017 or so.


COMPONENT-DEPENDS-ON is used for all dependencies.

Use :in-order-to everywhere you used to use :do-first, if ever.


new attribute of COMPONENT

accepts an arbitrary feature expression

e.g. :if-feature (:and :sbcl (:or :x86 :x86-64))

Beware: no magic reading in keyword package — use : syntax

Replaces the misguided :if-component-dep-fails attribute of MODULE

could not be salvaged when refactoring TRAVERSE

Dropped that attribute and the accompanying :feature feature

Limited backward compatibility just for SB-GROVEL and co.

ASDF 3’s new DEFSYSTEM features


ASDF3 ~70% slower than ASDF2

Slightly faster when *RESOLVE-SYMLINKS* is false (default true)

ASDF2 much faster than ASDF1: don’t (ab)use LIST data structures

Underneath, ASDF3 does much more work, correctly

Cache expensive computations in hash-table in dynamic variable

One package per file

ASDF 3 was rewritten in the style of faslpath and quick-build

Each file has its own DEFPACKAGE

Actually uses UIOP/PACKAGE:DEFINE-PACKAGE for hot-upgrade and reexport

Future: actually support faslpath or quick-build dependencies?


build a single Lisp file from all the source in a system

Variant MONOLITHIC-CONCATENATE-SOURCE-OP to transclude dependencies

Used by ASDF itself to split it in multiple files

ASDF has more than doubled in size between ASDF 2.26 and ASDF 3.0.1

Had already increased manifold since ASDF 1.

It just does that much more work.

The ASDF 1 bits have actually been much simplified.

ASDF-BUNDLE was merged into ASDF.

Fewer headaches for users of ECL

More features for users of other implementations

Can create a single fasl per system with fasl-op

Makes software delivery easier.

Support for pre-compiled systems.

SBCL patch to use that for contribs.


create standalone executables on supported implementations

Supported: clisp ccl cmucl ecl lispworks sbcl scl

See example in test/hello-world-example.asd

Uses image hooks above.


A generic operation that will do the “right thing” for each system

Not super supported yet, but the future(?)

TODO: generic-load-op, build-op, etc.


Fixed :force to actually work as advertised by ASDF 1.

Accepts :all, t, or a list of system names

Also implemented :force-not and based on it require-system

Can’t force builtin systems (e.g. SB-BSD-SOCKETS)

WARNING: rpg may revert that FORCE has precedence over FORCE-NOT


name be recognized by defsystem as located in foo.asd

Somewhat backward compatible

in ASDF2, you had to manually ensure foo.asd was loaded beforehand

in ASDF3, works automatically

Allows sensible way to define multiple systems in an .asd file.

See iolib.asd

Internals: grep for function primary-system-name

Deferred warnings

Don’t drop info on yet undefined functions

Supported: allegro ccl cmucl sbcl scl

Disabled by default.

Enable it: #+asdf3 (setf asdf::*warnings-file-type* (asdf::warnings-file-type))

Dump info for foo.lisp in foo.sbcl-warnings

Checked at the end of the build on each system


As if a WITH-COMPILATION-UNIT around each system

TRUENAME resolution

Now can be reliably turned off:

(setf asdf:*resolve-symlinks* nil)

Useful if TRUENAME is slow or bogus on your OS

Necessary if using symlinks to content-addressed storage

e.g. the Google build system

VERSION strings

Warnings if you don’t follow the convention of VERSION-SATISFIES

Regex: “[0-9]+(\.[0-9]+)+”

version-satisfies now uses uiop:version<= for comparison

No more checking for a same major version number

Was undocumented behavior since ASDF 1, still in version-compatible-p


Now also accept (:read-file-form <path> :at <formpath>)

Now also accept (:read-file-line <path> :at <linenum>)

:at optional, defaults to 0, 0-based

<formpath> as per UIOP:ACCESS-AT

e.g. (:read-file-form "specials.lisp" :at (2 2))

same as (:read-file-form "specials.lisp" :at (third third))

Easier to manage versioning from master location

See poiu.asd, poiu.lisp


ASDF 3 will always start by automatically upgrade itself

Proviso against downgrade, with warning

Just have the asdf/ tree somewhere in your source-registry

Only sane way to deal with potential upgrade

Otherwise, if any recursive dependency loads ASDF, kaboom

not algorithmically detectable: .asd files not declarative


also the :PROPERTIES initarg of DEFSYSTEM

Still works for now

To be retired before a hypothetical future ASDF 4.

Used by few, never with any name convention.

Recommended instead: use DEFCLASS a subclass of ASDF:SYSTEM

to add new slots and/or initargs. Then use :defsystem-depends-on and :class in defsystem

We added :homepage :bug-tracker :mailto :long-name to defsystem

The only common metadata used, though never in the same way


Completely refactored. Many renamings after checking Quicklisp.

Some sorry features were excised

OPERATION-DONE-P is simplified and now well-specified

FIND-COMPONENT will pass component objects through

a corresponding FIND-OPERATION replaces MAKE-SUB-OPERATION

Convenience methods

Added to many exported generic functions:

input-files output-files component-depends-on operate

You can e.g.: (input-files 'compile-op '(system1 "file1"))

Instead of (input-files (make-instance 'compile-op) (find-component 'system1 "file1"))

Makes it much easier to interact with ASDF at the REPL

Debugging ASDF extensions and modifications easier

inline-methods can now be unqualified

Fixes lp#485393

Great for defining test-op methods:

(defsystem foo/test ... :perform (test-op (o s) (symbol-call :foo-test :run-tests)))

NB: Unhappily, this is works in ASDF 3 but is circular in ASDF2:

(defsystem foo ... :in-order-to ((test-op (test-op foo/test))))

:ASDF3 in *features*

#+asdf3 present since pre-release ASDF 2.27

Typically used in :depends-on (#-asdf3 :asdf-driver)

Can protect code not supported in all of ASDF 1, ASDF 2

No support for ASDF < 2.014.6 (original Quicklisp ASDF)

SLIME support

Significantly enhanced (Use 2013-02 or later)

For around-compile hook support, in ~/.swank.lisp add:

(in-package :swank)

(pushnew 'try-compile-file-with-asdf *compile-file-for-emacs-hook*)


asdf.texinfo only covers the DEFSYSTEM part

It doesn’t cover new operations or internals

UIOP is only documented in docstrings

All in all, very limited. But examples abound.


Regression test framework massively improved

Regression-driven, with plenty of new test cases

Still far cry from covering all desired behavior

UIOP largely untested

Automated tests: abcl allegro allegromodern ccl clisp

cmucl ecl ecl_bytecodes lispworks sbcl scl xcl

Manual tests: gcl2.6 genera lispworks-personal-edition

Untested on cormancl mkcl rmcl

ASDF 3’s new portability layer


“Utilities for Implementation- and OS- Portability”

a separately-usable library for Common Lisp runtime support.

Pathnames, Filesystem, RUN-PROGRAM, compilation, image…

Formerly known as ASDF-DRIVER, formerly ASDF-UTILS


Transcluded in asdf.lisp thanks to MONOLITHIC-CONCATENATE-SOURCE-OP

Also more portable alias :asdf-driver for versions before 2.32

Use it: :depends-on (#-asdf3 :asdf-driver) or if you insist :depends-on (:uiop)


Updates on each and every implementation

9 active: abcl allegro ccl clisp cmucl ecl lispworks sbcl scl

6 mostly dead: gcl2.6 genera xcl cormancl rmcl mkcl

Variants: allegromodern lispworks-personal-edition ecl_bytecodes

Festering horror: pathnames.

Worst: “logical” pathnames.

CL Pathnames: THE HORROR!

CLHS horribly misdesigned. Countless bugs in ASDF and CL implementations.

FAIL: #p”foo/bar” can never be portable (separator OS dependent)

Pray your *default-pathname-defaults* isn’t “logical”

FAIL: no sure way to make a non-wildcard pathname

Pray your filesystem doesn’t contain files with * in name

FAIL: even MAKE-PATHNAME isn’t portable

Host, device, :unspecific, wildcard escaping, etc.

FAIL: even MERGE-PATHNAMES isn’t portable

Host and device defaulting will bite you eventually

FAIL: No portability across implementations on a same OS

FAIL: logical pathnames are unusable in practice. Avoid.

Not portable, inefficient, not modular, unusable DIRECTORY

If you can initialize them portably, you don’t need to use them.

FAIL: Can never be fixed

implementers each maintain their own backward-compatibility

users can’t portably fix it and hook into OPEN, LOAD, #P, etc.

Semi-solution: UIOP/PATHNAME

Don’t use #P”foo/bar”, have your own string parser

ASDF uses PARSE-UNIX-NAMESTRING for relative path specs

So path specs are portable, even when not on Unix,

as long as you don’t use in names any character that is

a valid separator, wildcard or escape on any platform.

Do our own pathname type defaulting.

Use MERGE-PATHNAMES*, MAKE-PATHNAME* instead of CLHS primitives



Many more working around CLHS braindeadness

Supersedes cl-fad

Still, can’t save you from impl-dep wild pathnames


In package UIOP/PACKAGE, also exported from UIOP

A better DEFPACKAGE variant

Works well for hot upgrade, fixes existing packages

Has (:mix pkg1 pkg2 pkg3 ...) instead of (:use ...)

Also has (:reexport pkg1 pkg2 pkg3 ...)

Also has PACKAGE-DEFINITION-FORM to inspect current package state

Still within limitations of CL packages.

UIOP/IMAGE, image lifecycle support

Included in UOIP

Must call RESTORE-IMAGE early during program initialization

Done implicitly by DUMP-IMAGE with :executable t

Will initialize *COMMAND-LINE-ARGUMENTS* and more



replaces the broken old misdesigned RUN-SHELL-COMMAND


Misdesign copied from MK-DEFSYSTEM

RUN-PROGRAM portable to all Windows & Unix CL (not Genera)

Can sensibly capture output, via SLURP-INPUT-STREAM

(run-program '("ls" "-l") :output :lines)


Higher-level interface available in system inferior-shell

Conditions control

Will selectively muffled conditions




Empty by default for backward-compatibility by user demand

Suggested: (setf uiop:*uninteresting-conditions* (uiop:*usual-uninteresting-conditions*))

Supersedes code from XCVB-DRIVER, QRes, QPX


On ASDF3, does the Right Thing(tm) on all implementations

Supports output-translation, deferred-warnings, etc.

Supports ECL and MKCL linkable object in addition to FASL

Supports .lib in CLISP, CFASL in SBCL, etc.


load favorite debugging primitives in current package

Put path to yours in uiop/utility:*uiop-debug-utility*

See mine in uoip/contrib/debug.lisp

(DBG :tag expr1 expr2 ... last-expr)

Also in UIOP

common-lisp: compatibility with obsolete CL implementations

utilities: plenty of general-purpose utilities

filesystem: chdir, directory-files, etc.

stream: with-safe-io-syntax, format!, with-temporary-file

os: getenv, etc.

configuration: help with configuration


UIOP is only documented in docstrings

How to extend ASDF

How to implement an extension

define new component and/or operation subclasses

define appropriate methods:

at least component-depends-on, input-files, output-files, perform

also operation-description for debugging.

see cffi/grovel/asdf.lisp

see cl-protobufs/asdf-support.lisp

Troubleshooting ASDF

Look at error messages

Look at the backtrace

Trace relevant functions

perform-plan, perform

input-files, output-files

Often requested: load-only component class

some kind of CL-SOURCE-FILE for which LOAD-OP means LOAD-SOURCE-OP

Beware: defeats executable creation!

Maybe instead you want run-time evaluation in your Lisp file:

(foo '(some data)) or even (eval '(some expression))

Support other languages?

Can they be loaded in-image?

Yes: CL becomes a platform (e.g. use cl-python)

No: second class citizens

Dependency generation?


Components of type SYSTEM ?

Yes: that’s what ASDF:DEFSYSTEM does!

use :depends-on (foo)

No: mk-defsystem idiom, not supported

do NOT use :components ((:system foo))

Horror .asd file?

mcclim.asd before ASDF 3 refactoring

gbbopen.asd is still pretty complex

Really, any .asd file with non defsystem forms.


Future Work?

More declarative DEFSYSTEM

Forbid or specially treat .asd files with forms beside defsystem

Keep deferred warnings by default?

Must fix tens of systems in quicklisp that would fail on SBCL.

Make further cleanups to the object model?

Never going to happen: if it’s not backward…


Move to XCVB, quick-build

or move to Racket? R7RS?

Lessons Learned

ASDF design discovered by evolution, not intelligent design

Big design constraint was interactive development in live image

It is possible to write code portably in CL, by using UIOP.

Whether it’s a good idea is a different question

Some things in CL can never be fixed. e.g. pathnames.

Not even possible to start thinking of better

namespace management, continuations, type systems, etc.

The test suite matters a whole lot

TODO: automate tests with quicklisp and cl-test-grid

ASDF 3 is now available in stores near you

Download and install in your source registry

Demand it from your implementation vendors!

Meanwhile, ASDF 2 ubiquitous at long last.

ASDF 3 needs new maintainers

Must remain backward compatible — be gentle with it!