<s>
C--	B-Language
(	O
pronounced	O
C	B-Language
minus	I-Language
minus	I-Language
)	O
is	O
a	O
C-like	O
programming	O
language	O
.	O
</s>
<s>
Its	O
creators	O
,	O
functional	B-Language
programming	I-Language
researchers	O
Simon	O
Peyton	O
Jones	O
and	O
Norman	O
Ramsey	O
,	O
designed	O
it	O
to	O
be	O
generated	O
mainly	O
by	O
compilers	B-Language
for	O
very	B-Language
high-level	I-Language
languages	I-Language
rather	O
than	O
written	O
by	O
human	O
programmers	O
.	O
</s>
<s>
Unlike	O
many	O
other	O
intermediate	B-Application
languages	I-Application
,	O
its	O
representation	O
is	O
plain	O
ASCII	B-Protocol
text	I-Protocol
,	O
not	O
bytecode	O
or	O
another	O
binary	O
format	O
.	O
</s>
<s>
C--	B-Language
is	O
a	O
"	O
portable	O
assembly	B-Language
language	I-Language
"	O
,	O
designed	O
to	O
ease	O
the	O
implementation	O
of	O
compilers	B-Language
that	O
produce	O
high-quality	O
machine	B-Language
code	I-Language
.	O
</s>
<s>
This	O
is	O
done	O
by	O
delegating	O
low-level	O
code-generation	B-Application
and	O
program	O
optimization	O
to	O
a	O
C--	B-Language
compiler	B-Language
.	O
</s>
<s>
The	O
language	O
's	O
syntax	O
borrows	O
heavily	O
from	O
C	B-Language
while	O
omitting	O
or	O
changing	O
standard	O
C	B-Language
features	O
such	O
as	O
variadic	B-Language
functions	I-Language
,	O
pointer	O
syntax	O
,	O
and	O
aspects	O
of	O
C	B-Language
's	O
type	O
system	O
,	O
because	O
they	O
hamper	O
essential	O
features	O
of	O
C--	B-Language
and	O
ease	O
of	O
code-generation	B-Application
.	O
</s>
<s>
The	O
name	O
of	O
the	O
language	O
is	O
an	O
in-joke	O
,	O
indicating	O
that	O
C--	B-Language
is	O
a	O
reduced	O
form	O
of	O
C	B-Language
,	O
in	O
the	O
same	O
way	O
that	O
C++	B-Language
is	O
basically	O
an	O
expanded	O
form	O
of	O
C	B-Language
.	O
(	O
in	O
C	B-Language
,	O
--	O
and	O
++	O
mean	O
"	O
decrement	O
"	O
and	O
"	O
increment	O
,	O
"	O
respectively	O
.	O
)	O
</s>
<s>
Work	O
on	O
C--	B-Language
began	O
in	O
the	O
late	O
1990s	O
.	O
</s>
<s>
Since	O
writing	O
a	O
custom	O
code	B-Application
generator	I-Application
is	O
a	O
challenge	O
in	O
itself	O
,	O
and	O
the	O
compiler	B-Language
backends	O
available	O
to	O
researchers	O
at	O
that	O
time	O
were	O
complex	O
and	O
poorly	O
documented	O
,	O
several	O
projects	O
had	O
written	O
compilers	B-Language
which	O
generated	O
C	B-Language
code	O
(	O
for	O
instance	O
,	O
the	O
original	O
Modula-3	B-Language
compiler	B-Language
)	O
.	O
</s>
<s>
However	O
,	O
C	B-Language
is	O
a	O
poor	O
choice	O
for	O
functional	B-Language
languages	I-Language
:	O
it	O
does	O
not	O
guarantee	O
tail-call	B-Language
optimization	I-Language
,	O
or	O
support	O
accurate	O
garbage	B-General_Concept
collection	I-General_Concept
or	O
efficient	O
exception	B-General_Concept
handling	I-General_Concept
.	O
</s>
<s>
C--	B-Language
is	O
a	O
tightly-defined	O
simpler	O
alternative	O
to	O
C	B-Language
which	O
supports	O
all	O
of	O
these	O
.	O
</s>
<s>
Its	O
most	O
innovative	O
feature	O
is	O
a	O
run-time	O
interface	O
which	O
allows	O
writing	O
of	O
portable	O
garbage	B-General_Concept
collectors	I-General_Concept
,	O
exception	B-General_Concept
handling	I-General_Concept
systems	O
and	O
other	O
run-time	O
features	O
which	O
work	O
with	O
any	O
C--	B-Language
compiler	B-Language
.	O
</s>
<s>
The	O
first	O
version	O
of	O
C--	B-Language
was	O
released	O
in	O
April	O
1998	O
as	O
a	O
MSRA	O
paper	O
,	O
accompanied	O
by	O
a	O
January	O
1999	O
paper	O
on	O
garbage	B-General_Concept
collection	I-General_Concept
.	O
</s>
<s>
Two	O
sets	O
of	O
major	O
changes	O
proposed	O
in	O
2000	O
by	O
Norman	O
Ramsey	O
(	O
"	O
Proposed	O
Changes	O
"	O
)	O
and	O
Christian	O
Lindig	O
(	O
"	O
A	O
New	O
Grammar	O
"	O
)	O
led	O
to	O
C--	B-Language
version	O
2	O
,	O
which	O
was	O
finalized	O
around	O
2004	O
and	O
officially	O
released	O
in	O
2005	O
.	O
</s>
<s>
The	O
C--	B-Language
type	O
system	O
is	O
designed	O
to	O
reflect	O
constraints	O
imposed	O
by	O
hardware	O
rather	O
than	O
conventions	O
imposed	O
by	O
higher-level	O
languages	O
.	O
</s>
<s>
A	O
value	O
stored	O
in	O
a	O
register	O
or	O
memory	O
may	O
have	O
only	O
one	O
type	O
:	O
bit-vector	B-Data_Structure
.	O
</s>
<s>
However	O
,	O
bit-vector	B-Data_Structure
is	O
a	O
polymorphic	B-Application
type	O
which	O
comes	O
in	O
several	O
widths	O
,	O
e.g.	O
</s>
<s>
In	O
addition	O
to	O
the	O
bit-vector	B-Data_Structure
type	O
,	O
C--	B-Language
provides	O
a	O
boolean	O
type	O
,	O
which	O
can	O
be	O
computed	O
by	O
expressions	O
and	O
used	O
for	O
control	O
flow	O
but	O
cannot	O
be	O
stored	O
in	O
a	O
register	O
or	O
memory	O
.	O
</s>
<s>
As	O
in	O
an	O
assembly	B-Language
language	I-Language
,	O
any	O
higher	O
type	O
discipline	O
,	O
such	O
as	O
distinctions	O
between	O
signed	O
,	O
unsigned	O
,	O
float	O
,	O
and	O
pointer	O
,	O
is	O
imposed	O
by	O
the	O
C--	B-Language
operators	O
or	O
other	O
syntactic	O
constructs	O
.	O
</s>
<s>
C--	B-Language
is	O
not	O
type-checked	O
,	O
nor	O
does	O
it	O
enforce	O
or	O
check	O
the	O
calling	O
convention	O
.	O
</s>
<s>
C--	B-Language
version	O
2	O
removes	O
the	O
distinction	O
between	O
bit-vector	B-Data_Structure
and	O
floating-point	O
types	O
.	O
</s>
<s>
Special	O
types	O
for	O
pointers	O
and	O
the	O
native	O
word	O
were	O
introduced	O
,	O
although	O
they	O
are	O
mapped	O
to	O
a	O
bit-vector	B-Data_Structure
with	O
a	O
target-dependent	O
length	O
.	O
</s>
<s>
The	O
specification	O
page	O
of	O
C--	B-Language
lists	O
a	O
few	O
implementations	O
of	O
C--	B-Language
.	O
</s>
<s>
The	O
"	O
most	O
actively	O
developed	O
"	O
compiler	B-Language
,	O
Quick	O
C--	B-Language
,	O
was	O
abandoned	O
in	O
2013	O
.	O
</s>
<s>
Some	O
developers	O
of	O
C--	B-Language
,	O
including	O
Simon	O
Peyton	O
Jones	O
,	O
João	O
Dias	O
,	O
and	O
Norman	O
Ramsey	O
,	O
work	O
or	O
have	O
worked	O
on	O
GHC	O
,	O
whose	O
development	O
has	O
led	O
to	O
extensions	O
in	O
the	O
C--	B-Language
language	O
,	O
forming	O
the	O
Cmm	O
dialect	O
which	O
uses	O
the	O
C	B-Language
preprocessor	I-Language
for	O
ergonomics	O
.	O
</s>
<s>
GHC	O
backends	O
are	O
responsible	O
for	O
further	O
transforming	O
C--	B-Language
into	O
executable	O
code	O
,	O
via	O
LLVM	B-Application
IR	B-Application
,	O
slow	O
C	B-Language
,	O
or	O
directly	O
through	O
the	O
built-in	O
native	O
backend	O
.	O
</s>
<s>
Despite	O
the	O
original	O
intention	O
,	O
GHC	O
does	O
perform	O
many	O
of	O
its	O
generic	O
optimizations	O
on	O
C--	B-Language
.	O
</s>
<s>
As	O
with	O
other	O
compiler	B-Language
IRs	B-Application
,	O
the	O
C--	B-Language
representation	O
can	O
be	O
dumped	O
for	O
debugging	O
.	O
</s>
