<s>
The	O
fat	B-Language
comma	I-Language
(	O
also	O
termed	O
hash	B-Language
rocket	I-Language
in	O
Ruby	B-Language
and	O
a	O
fat	B-Language
arrow	I-Language
in	O
JavaScript	B-Language
)	O
is	O
a	O
syntactic	O
construction	O
that	O
appears	O
in	O
a	O
position	O
in	O
a	O
function	O
call	O
(	O
or	O
definition	O
)	O
where	O
a	O
comma	O
would	O
usually	O
appear	O
.	O
</s>
<s>
It	O
is	O
primarily	O
associated	O
with	O
PHP	B-Application
,	O
Ruby	B-Language
and	O
Perl	B-Language
programming	I-Language
languages	I-Language
,	O
which	O
use	O
it	O
to	O
declare	O
hashes	B-Algorithm
.	O
</s>
<s>
Using	O
a	O
fat	B-Language
comma	I-Language
to	O
bind	O
key-value	O
pairs	O
in	O
a	O
hash	O
,	O
instead	O
of	O
using	O
a	O
comma	O
,	O
is	O
considered	O
an	O
example	O
of	O
good	O
idiomatic	O
Perl	B-Language
.	O
</s>
<s>
In	O
CoffeeScript	B-Application
and	O
TypeScript	B-Language
,	O
the	O
fat	B-Language
comma	I-Language
is	O
used	O
to	O
declare	O
a	O
function	O
that	O
is	O
bound	O
to	O
this	O
.	O
</s>
<s>
The	O
ALGOL	O
"	O
fat	B-Language
comma	I-Language
"	O
is	O
semantically	O
identical	O
to	O
the	O
comma	O
.	O
</s>
<s>
The	O
"	O
fat	B-Language
comma	I-Language
"	O
forces	O
the	O
word	O
to	O
its	O
left	O
to	O
be	O
interpreted	O
as	O
a	O
string	O
.	O
</s>
<s>
the	O
following	O
use	O
of	O
the	O
fat	B-Language
comma	I-Language
would	O
be	O
legal	O
and	O
idiomatic	O
:	O
</s>
<s>
The	O
result	O
is	O
easier-to-read	O
code	O
,	O
with	O
a	O
stronger	O
emphasis	O
on	O
the	O
name-value	O
pairing	O
of	O
associative	B-Application
arrays	I-Application
.	O
</s>
<s>
In	O
PHP	B-Application
,	O
the	O
fat	B-Language
comma	I-Language
is	O
termed	O
a	O
double	O
arrow	O
,	O
and	O
is	O
used	O
to	O
specify	O
key/value	O
relationships	O
when	O
declaring	O
an	O
array	O
.	O
</s>
<s>
Unlike	O
in	O
Perl	B-Language
,	O
the	O
double	O
arrow	O
does	O
not	O
treat	O
what	O
comes	O
before	O
it	O
as	O
a	O
bare	O
word	O
,	O
but	O
rather	O
evaluates	O
it	O
.	O
</s>
<s>
In	O
Ruby	B-Language
,	O
the	O
fat	B-Language
comma	I-Language
is	O
the	O
token	O
to	O
create	O
hashes	B-Algorithm
.	O
</s>
<s>
Ruby	B-Language
1.9	O
introduced	O
a	O
special	O
syntax	O
to	O
use	O
symbols	O
as	O
barewords	O
.	O
</s>
<s>
In	O
Ruby	B-Language
,	O
the	O
fat	B-Language
comma	I-Language
is	O
called	O
a	O
hash	B-Language
rocket	I-Language
.	O
</s>
<s>
The	O
fat	B-Language
arrow	I-Language
is	O
used	O
to	O
declare	O
single	O
expression	O
anonymous	B-General_Concept
functions	I-General_Concept
in	O
JavaScript	B-Language
,	O
and	O
C	B-Application
sharp	I-Application
.	O
</s>
