<s>
Prolog++	B-Language
is	O
an	O
object-oriented	B-Language
toolkit	O
for	O
the	O
Prolog	B-Language
logic	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
It	O
allows	O
classes	O
and	O
class	B-Language
hierarchies	I-Language
to	O
be	O
created	O
within	O
Prolog	B-Language
programs	O
.	O
</s>
<s>
Prolog++	B-Language
was	O
developed	O
by	O
LPA	O
and	O
first	O
released	O
in	O
1989	O
for	O
MS-DOS	B-Application
PCs	O
.	O
</s>
<s>
A	O
book	O
entitled	O
'	O
Prolog++	B-Language
The	O
Power	O
of	O
Object-Oriented	B-Language
and	O
Logic	B-Language
Programming	I-Language
 '	O
by	O
Chris	O
Moss	O
was	O
published	O
by	O
Addison-Wesley	O
in	O
1994	O
.	O
</s>
<s>
Currently	O
,	O
Prolog++	B-Language
is	O
available	O
as	O
an	O
add-on	O
to	O
LPA	O
Prolog	B-Language
for	O
Windows	O
.	O
</s>
<s>
Three	O
other	O
approaches	O
to	O
object-oriented	B-Language
Prolog	B-Language
include	O
PDC	O
Visual	B-Application
Prolog	I-Application
(	O
once	O
known	O
as	O
Borland	O
Turbo	B-Application
Prolog	I-Application
)	O
,	O
SICStus	B-Language
Prolog	I-Language
and	O
the	O
almost	O
implementation-neutral	O
Logtalk	B-Language
framework	O
.	O
</s>
