<s>
occam	B-Language
is	O
a	O
programming	O
language	O
which	O
is	O
concurrent	B-Architecture
and	O
builds	O
on	O
the	O
communicating	O
sequential	O
processes	O
(	O
CSP	O
)	O
process	O
algebra	O
,	O
and	O
shares	O
many	O
of	O
its	O
features	O
.	O
</s>
<s>
It	O
is	O
named	O
after	O
philosopher	O
William	O
of	O
Ockham	O
after	O
whom	O
Occam	B-Language
's	O
razor	O
is	O
named	O
.	O
</s>
<s>
occam	B-Language
is	O
an	O
imperative	B-Application
procedural	B-Application
language	I-Application
(	O
such	O
as	O
Pascal	B-Application
)	O
.	O
</s>
<s>
It	O
was	O
developed	O
by	O
David	O
May	O
and	O
others	O
at	O
Inmos	O
(	O
trademark	O
INMOS	O
)	O
,	O
advised	O
by	O
Tony	O
Hoare	O
,	O
as	O
the	O
native	O
programming	O
language	O
for	O
their	O
transputer	B-General_Concept
microprocessors	B-Architecture
,	O
but	O
implementations	O
for	O
other	O
platforms	O
are	O
available	O
.	O
</s>
<s>
The	O
most	O
widely	O
known	O
version	O
is	O
occam	B-Language
2	I-Language
;	O
its	O
programming	O
manual	O
was	O
written	O
by	O
Steven	O
Ericsson-Zenith	O
and	O
others	O
at	O
Inmos	O
.	O
</s>
<s>
This	O
feature	O
,	O
named	O
the	O
off-side	B-Language
rule	I-Language
,	O
is	O
also	O
found	O
in	O
other	O
languages	O
such	O
as	O
Haskell	B-Language
and	O
Python	B-Language
.	O
</s>
<s>
Communication	O
between	O
processes	O
work	O
through	O
named	O
channels	B-Operating_System
.	O
</s>
<s>
However	O
,	O
the	O
program	O
will	O
neither	O
spin	O
nor	O
poll	O
;	O
thus	O
terms	O
like	O
wait	O
,	O
hang	O
or	O
yield	O
may	O
also	O
convey	O
the	O
behaviour	O
;	O
also	O
in	O
the	O
context	O
that	O
it	O
will	O
not	O
block	B-Operating_System
other	O
independent	O
processes	O
from	O
running	O
.	O
)	O
</s>
<s>
This	O
will	O
read	O
data	O
from	O
channels	B-Operating_System
c1	O
or	O
c2	O
(	O
whichever	O
is	O
ready	O
)	O
and	O
pass	O
it	O
into	O
a	O
merged	O
channel	O
.	O
</s>
<s>
occam	B-Language
1	O
(	O
released	O
1983	O
)	O
was	O
a	O
preliminary	O
version	O
of	O
the	O
language	O
which	O
borrowed	O
from	O
David	O
May	O
's	O
work	O
on	O
EPL	O
and	O
Tony	O
Hoare	O
's	O
CSP	O
.	O
</s>
<s>
occam	B-Language
2	I-Language
is	O
an	O
extension	O
produced	O
by	O
Inmos	O
Ltd	O
in	O
1987	O
that	O
adds	O
floating-point	B-Algorithm
support	O
,	O
functions	O
,	O
multi-dimensional	O
arrays	O
and	O
more	O
data	O
types	O
such	O
as	O
varying	O
sizes	O
of	O
integers	O
(	O
INT16	O
,	O
INT32	O
)	O
and	O
bytes	O
.	O
</s>
<s>
With	O
this	O
revision	O
,	O
occam	B-Language
became	O
a	O
language	O
able	O
to	O
express	O
useful	O
programs	O
,	O
whereas	O
occam	B-Language
1	O
was	O
more	O
suited	O
to	O
examining	O
algorithms	O
and	O
exploring	O
the	O
new	O
language	O
(	O
however	O
,	O
the	O
occam	B-Language
1	O
compiler	O
was	O
written	O
in	O
occam	B-Language
1	O
,	O
so	O
there	O
is	O
an	O
existence	O
proof	O
that	O
reasonably	O
sized	O
,	O
useful	O
programs	O
could	O
be	O
written	O
in	O
occam	B-Language
1	O
,	O
despite	O
its	O
limits	O
)	O
.	O
</s>
<s>
occam	B-Language
2.1	I-Language
was	O
the	O
last	O
of	O
the	O
series	O
of	O
occam	B-Language
language	O
developments	O
contributed	O
by	O
Inmos	O
.	O
</s>
<s>
Defined	O
in	O
1994	O
,	O
it	O
was	O
influenced	O
by	O
an	O
earlier	O
proposal	O
for	O
an	O
occam	B-Language
3	I-Language
language	O
(	O
also	O
referred	O
to	O
as	O
"	O
occam91	O
"	O
during	O
its	O
early	O
development	O
)	O
created	O
by	O
Geoff	O
Barrett	O
at	O
Inmos	O
in	O
the	O
early	O
1990s	O
.	O
</s>
<s>
A	O
revised	O
Reference	O
Manual	O
describing	O
occam	B-Language
3	I-Language
was	O
distributed	O
for	O
community	O
comment	O
,	O
but	O
the	O
language	O
was	O
never	O
fully	O
implemented	O
in	O
a	O
compiler	O
.	O
</s>
<s>
occam	B-Language
2.1	I-Language
introduced	O
several	O
new	O
features	O
to	O
occam	B-Language
2	I-Language
,	O
including	O
:	O
</s>
<s>
occam-π	B-Language
is	O
the	O
common	O
name	O
for	O
the	O
occam	B-Language
variant	O
implemented	O
by	O
later	O
versions	O
of	O
the	O
Kent	O
Retargetable	O
occam	B-Language
Compiler	O
(	O
KRoC	B-Application
)	O
.	O
</s>
<s>
The	O
addition	O
of	O
the	O
symbol	O
π	O
(	O
pi	O
)	O
to	O
the	O
occam	B-Language
name	O
is	O
an	O
allusion	O
to	O
KRoC	B-Application
occam	B-Language
including	O
several	O
ideas	O
inspired	O
by	O
the	O
π-calculus	O
.	O
</s>
<s>
It	O
contains	O
several	O
significant	O
extensions	O
to	O
the	O
occam	B-Language
2.1	I-Language
compiler	O
,	O
for	O
example	O
:	O
</s>
