<s>
In	O
computing	O
,	O
a	O
channel	O
is	O
a	O
model	O
for	O
interprocess	B-Operating_System
communication	I-Operating_System
and	O
synchronization	O
via	O
message	B-Architecture
passing	I-Architecture
.	O
</s>
<s>
A	O
message	O
may	O
be	O
sent	O
over	O
a	O
channel	O
,	O
and	O
another	O
process	O
or	O
thread	O
is	O
able	O
to	O
receive	O
messages	O
sent	O
over	O
a	O
channel	O
it	O
has	O
a	O
reference	O
to	O
,	O
as	O
a	O
stream	B-Architecture
.	O
</s>
<s>
The	O
multithreading	B-General_Concept
library	O
,	O
libthread	O
,	O
which	O
was	O
first	O
created	O
for	O
the	O
operating	O
system	O
Plan	B-Operating_System
9	I-Operating_System
,	O
offers	O
inter-thread	B-Operating_System
communication	I-Operating_System
based	O
on	O
fixed-size	O
channels	O
.	O
</s>
<s>
The	O
OCaml	B-Language
event	O
module	O
offers	O
typed	O
channels	O
for	O
synchronization	O
.	O
</s>
<s>
The	O
Love2D	B-Application
library	O
which	O
is	O
part	O
of	O
the	O
Lua	B-Language
programming	I-Language
language	I-Language
implements	O
channels	O
with	O
push	O
and	O
pop	O
operations	O
similar	O
to	O
stacks	O
.	O
</s>
<s>
In	O
this	O
example	O
,	O
two	O
hardware	B-General_Concept
threads	I-General_Concept
are	O
started	O
on	O
the	O
XMOS	O
,	O
running	O
the	O
two	O
lines	O
in	O
the	O
"	O
par	O
"	O
block	O
.	O
</s>
<s>
Rust	B-Application
provides	O
asynchronous	O
channels	O
for	O
communication	O
between	O
threads	O
.	O
</s>
<s>
In	O
addition	O
to	O
their	O
fundamental	O
use	O
for	O
interprocess	B-Operating_System
communication	I-Operating_System
,	O
channels	O
can	O
be	O
used	O
as	O
a	O
primitive	O
to	O
implement	O
various	O
other	O
concurrent	O
programming	O
constructs	O
which	O
can	O
be	O
realized	O
as	O
streams	O
.	O
</s>
<s>
For	O
example	O
,	O
channels	O
can	O
be	O
used	O
to	O
construct	O
futures	B-Operating_System
and	I-Operating_System
promises	I-Operating_System
,	O
where	O
a	O
future	O
is	O
a	O
one-element	O
channel	O
,	O
and	O
a	O
promise	O
is	O
a	O
process	O
that	O
sends	O
to	O
the	O
channel	O
,	O
fulfilling	O
the	O
future	O
.	O
</s>
