<s>
The	O
PCASTL	B-Language
(	O
an	O
acronym	O
for	O
by	O
Parent	O
and	O
Childset	O
Accessible	O
Syntax	B-Data_Structure
Tree	I-Data_Structure
Language	O
)	O
is	O
an	O
interpreted	O
high-level	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
The	O
PCASTL	B-Language
is	O
designed	O
to	O
ease	O
the	O
writing	O
of	O
self-modifying	B-Application
code	I-Application
.	O
</s>
<s>
The	O
language	O
has	O
reserved	O
words	O
parent	O
and	O
childset	O
to	O
access	O
the	O
nodes	O
of	O
the	O
syntax	B-Data_Structure
tree	I-Data_Structure
of	O
the	O
currently	O
written	O
code	O
.	O
</s>
<s>
The	O
syntax	O
of	O
PCASTL	B-Language
is	O
derived	O
from	O
programming	O
languages	O
C	B-Language
and	O
R	B-Language
.	O
The	O
source	O
of	O
R	B-Language
version	O
2.5.1	O
has	O
been	O
studied	O
to	O
write	O
the	O
grammar	O
and	O
the	O
lexer	B-Application
used	O
in	O
the	O
PCASTL	B-Language
interpreter	O
.	O
</s>
<s>
Like	O
in	O
R	B-Language
,	O
statements	O
can	O
,	O
but	O
do	O
not	O
have	O
to	O
,	O
be	O
separated	O
by	O
semicolons	O
.	O
</s>
<s>
Like	O
in	O
R	B-Language
,	O
a	O
variable	O
can	O
change	O
type	O
in	O
a	O
session	B-Protocol
.	O
</s>
<s>
Like	O
in	O
C	B-Language
and	O
R	B-Language
,	O
PCASTL	B-Language
uses	O
balanced	O
brackets	O
( {	O
and	O
}	O
)	O
to	O
make	O
blocks	O
.	O
</s>
<s>
Operators	O
found	O
in	O
PCASTL	B-Language
have	O
the	O
same	O
precedence	O
and	O
associativity	O
as	O
their	O
counterparts	O
in	O
C	B-Language
.	O
for	O
loops	O
are	O
defined	O
like	O
in	O
C	B-Language
.	O
++	O
and	O
--	O
operators	O
are	O
used	O
like	O
in	O
C	B-Language
to	O
increment	O
or	O
decrement	O
a	O
variable	O
before	O
or	O
after	O
it	O
is	O
used	O
in	O
its	O
expression	O
.	O
</s>
<s>
An	O
example	O
of	O
PCASTL	B-Language
using	O
the	O
for	O
reserved	O
word	O
and	O
the	O
++	O
operator	O
:	O
</s>
<s>
Functions	O
and	O
comments	O
in	O
PCASTL	B-Language
are	O
defined	O
like	O
in	O
R	B-Language
:	O
</s>
<s>
The	O
parent	O
reserved	O
word	O
gives	O
a	O
reference	O
to	O
the	O
parent	O
node	O
in	O
the	O
syntax	B-Data_Structure
tree	I-Data_Structure
of	O
the	O
code	O
where	O
the	O
word	O
is	O
placed	O
.	O
</s>
