<s>
Arc	B-Operating_System
is	O
a	O
programming	O
language	O
,	O
a	O
dialect	O
of	O
the	O
language	O
Lisp	B-Language
,	O
developed	O
by	O
Paul	O
Graham	O
and	O
Robert	O
Morris	O
.	O
</s>
<s>
It	O
is	O
free	B-License
and	I-License
open-source	I-License
software	I-License
released	O
under	O
the	O
Artistic	B-License
License	I-License
2.0	I-License
.	O
</s>
<s>
In	O
2001	O
,	O
Paul	O
Graham	O
announced	O
that	O
he	O
was	O
working	O
on	O
a	O
new	O
dialect	O
of	O
Lisp	B-Language
named	O
Arc	B-Operating_System
.	O
</s>
<s>
Over	O
the	O
years	O
since	O
,	O
he	O
has	O
written	O
several	O
essays	O
describing	O
features	O
or	O
goals	O
of	O
the	O
language	O
,	O
and	O
some	O
internal	O
projects	O
at	O
Graham	O
's	O
startup	O
business	O
incubator	O
named	O
Y	O
Combinator	O
have	O
been	O
written	O
in	O
Arc	B-Operating_System
,	O
most	O
notably	O
the	O
Hacker	B-Application
News	I-Application
web	O
forum	O
and	O
news	O
aggregator	O
program	O
.	O
</s>
<s>
Arc	B-Operating_System
is	O
written	O
in	O
Racket	B-Operating_System
.	O
</s>
<s>
While	O
many	O
of	O
the	O
goals	O
are	O
very	O
general	O
(	O
"	O
Arc	B-Operating_System
should	O
be	O
hackable	O
"	O
,	O
"	O
there	O
should	O
be	O
good	O
libraries	B-Library
"	O
)	O
,	O
he	O
did	O
give	O
some	O
specifics	O
.	O
</s>
<s>
He	O
also	O
stated	O
that	O
it	O
is	O
better	O
for	O
a	O
language	O
to	O
only	O
implement	O
a	O
small	O
number	O
of	O
axioms	O
,	O
even	O
when	O
that	O
means	O
the	O
language	O
may	O
not	O
have	O
features	O
that	O
large	O
organizations	O
want	O
,	O
such	O
as	O
object-orientation	B-Language
(	O
OO	O
)	O
.	O
</s>
<s>
At	O
Arc	B-Operating_System
's	O
introduction	O
in	O
2008	O
,	O
Graham	O
stated	O
one	O
of	O
its	O
benefits	O
was	O
its	O
brevity	O
.	O
</s>
<s>
A	O
controversy	O
among	O
Lisp	B-Language
programmers	O
is	O
whether	O
,	O
and	O
how	O
much	O
,	O
the	O
s-expressions	B-Protocol
of	O
the	O
language	O
should	O
be	O
complemented	O
by	O
other	O
forms	O
of	O
syntax	B-Application
.	O
</s>
<s>
Graham	O
thinks	O
that	O
added	O
syntax	B-Application
should	O
be	O
used	O
in	O
situations	O
where	O
pure	O
s-expressions	B-Protocol
would	O
be	O
overly	O
verbose	O
,	O
saying	O
,	O
"	O
I	O
do	O
n't	O
think	O
we	O
should	O
be	O
religiously	O
opposed	O
to	O
introducing	O
syntax	B-Application
into	O
Lisp.	O
"	O
</s>
<s>
When	O
released	O
in	O
2008	O
,	O
Arc	B-Operating_System
generated	O
mixed	O
reactions	O
,	O
with	O
some	O
calling	O
it	O
simply	O
an	O
extension	O
to	O
Lisp	B-Language
or	O
Scheme	B-Language
and	O
not	O
a	O
programming	O
language	O
in	O
its	O
own	O
right	O
.	O
</s>
<s>
Others	O
applauded	O
Arc	B-Operating_System
for	O
stripping	O
Lisp	B-Language
down	O
to	O
bare	O
essentials	O
.	O
</s>
<s>
Shortly	O
after	O
its	O
release	O
,	O
Arc	B-Operating_System
was	O
ported	O
to	O
JavaScript	B-Language
,	O
and	O
was	O
being	O
supported	O
by	O
Schemescript	O
,	O
an	O
integrated	B-Application
development	I-Application
environment	I-Application
(	O
IDE	O
)	O
based	O
on	O
Eclipse	B-Application
.	O
</s>
<s>
Hello	O
world	O
in	O
Arc	B-Operating_System
:	O
</s>
<s>
To	O
illustrate	O
Arc	B-Operating_System
's	O
terseness	O
,	O
Graham	O
uses	O
a	O
brief	O
program	O
.	O
</s>
<s>
The	O
first	O
publicly	O
released	O
version	O
of	O
Arc	B-Operating_System
was	O
made	O
available	O
on	O
29	O
January	O
2008	O
,	O
implemented	O
on	O
Racket	B-Operating_System
(	O
named	O
PLT-Scheme	O
then	O
)	O
.	O
</s>
<s>
The	O
release	O
comes	O
in	O
the	O
form	O
of	O
a	O
.tar	B-Application
archive	O
,	O
containing	O
the	O
Racket	B-Operating_System
source	O
code	O
for	O
Arc	B-Operating_System
.	O
</s>
<s>
The	O
forum	O
uses	O
the	O
same	O
program	O
that	O
Hacker	B-Application
News	I-Application
does	O
,	O
and	O
is	O
written	O
in	O
Arc	B-Operating_System
.	O
</s>
<s>
Due	O
to	O
lack	O
of	O
updates	O
in	O
the	O
official	O
Arc	B-Operating_System
branch	O
,	O
some	O
members	O
of	O
the	O
Arc	B-Operating_System
community	O
started	O
their	O
own	O
repositories	O
with	O
unofficial	O
modifications	O
,	O
extensions	O
,	O
and	O
libraries	B-Library
.	O
</s>
<s>
Rainbow	O
is	O
an	O
implementation	O
of	O
Arc	B-Operating_System
in	O
Java	B-Language
.	O
</s>
<s>
Arcadia	O
is	O
an	O
implementation	O
of	O
Arc	B-Operating_System
in	O
C	B-Language
.	O
</s>
