<s>
ASDF	O
(	O
Another	B-Language
System	I-Language
Definition	I-Language
Facility	I-Language
)	O
is	O
a	O
package	O
format	O
and	O
a	O
build	O
tool	O
for	O
Common	B-Language
Lisp	I-Language
libraries	O
.	O
</s>
<s>
It	O
is	O
analogous	O
to	O
tools	O
such	O
as	O
Make	B-Application
and	O
Ant	B-Application
.	O
</s>
<s>
ASDF	O
was	O
originally	O
designed	O
and	O
written	O
in	O
2001-2002	O
as	O
a	O
successor	O
for	O
a	O
previous	O
program	O
,	O
mk-defsystem	O
,	O
taking	O
advantage	O
of	O
Common	B-Language
Lisp	I-Language
features	O
such	O
as	O
CLOS	B-Application
and	O
pathname	O
support	O
.	O
</s>
<s>
It	O
has	O
since	O
expanded	O
to	O
become	O
the	O
default	O
build	O
tool	O
for	O
Common	B-Language
Lisp	I-Language
programs	O
.	O
</s>
<s>
It	O
is	O
now	O
used	O
as	O
the	O
basis	O
for	O
Common	B-Language
Lisp	I-Language
library	O
build	O
systems	O
,	O
and	O
dependency	O
managers	O
,	O
such	O
as	O
Quicklisp	O
,	O
cl-build	O
,	O
and	O
Debian	O
's	O
Common	B-Language
Lisp	I-Language
Controller	O
.	O
</s>
<s>
Most	O
maintained	O
,	O
open-source	O
Common	B-Language
Lisp	I-Language
libraries	O
are	O
buildable	O
and	O
installable	O
through	O
ASDF	O
.	O
</s>
<s>
Creating	O
and	O
defining	O
systems	O
installable	O
though	O
ASDF	O
is	O
done	O
through	O
the	O
creation	O
and	O
placement	O
of	O
one	O
or	O
more	O
system	O
definition	O
(	O
.asd	O
)	O
files	O
at	O
the	O
root	O
of	O
a	O
directory	O
containing	O
the	O
files	O
that	O
make	B-Application
up	O
the	O
system	O
.	O
</s>
<s>
ASDF	O
is	O
capable	O
of	O
automatically	O
compiling	B-Language
and	O
loading	O
lisp	O
source	O
code	O
,	O
as	O
well	O
as	O
automatically	O
building	O
and	O
linking	O
C	B-Language
programming	I-Language
language	I-Language
(	O
also	O
known	O
as	O
C	B-Language
source	O
code	O
)	O
.	O
</s>
<s>
It	O
contains	O
hooks	O
to	O
allow	O
for	O
definitions	O
of	O
alternate	O
compilers	B-Language
and	O
complex	O
treatment	O
of	O
custom	O
components	O
.	O
</s>
