<s>
Oz	B-Language
is	O
a	O
multiparadigm	O
programming	O
language	O
,	O
developed	O
in	O
the	O
Programming	O
Systems	O
Lab	O
at	O
Université	O
catholique	O
de	O
Louvain	O
,	O
for	O
programming	O
language	O
education	O
.	O
</s>
<s>
Oz	B-Language
was	O
first	O
designed	O
by	O
Gert	O
Smolka	O
and	O
his	O
students	O
in	O
1991	O
.	O
</s>
<s>
In	O
1996	O
,	O
development	O
of	O
Oz	B-Language
continued	O
in	O
cooperation	O
with	O
the	O
research	O
group	O
of	O
Seif	O
Haridi	O
and	O
Peter	O
Van	O
Roy	O
at	O
the	O
Swedish	O
Institute	O
of	O
Computer	O
Science	O
.	O
</s>
<s>
Since	O
1999	O
,	O
Oz	B-Language
has	O
been	O
continually	O
developed	O
by	O
an	O
international	O
group	O
,	O
the	O
Mozart	O
Consortium	O
,	O
which	O
originally	O
consisted	O
of	O
Saarland	O
University	O
,	O
the	O
Swedish	O
Institute	O
of	O
Computer	O
Science	O
,	O
and	O
the	O
Université	O
catholique	O
de	O
Louvain	O
.	O
</s>
<s>
The	O
Mozart	B-Language
Programming	I-Language
System	I-Language
is	O
the	O
primary	O
implementation	O
of	O
Oz	B-Language
.	O
</s>
<s>
Mozart	O
has	O
been	O
ported	O
to	O
Unix	B-Application
,	O
FreeBSD	B-Operating_System
,	O
Linux	B-Application
,	O
Windows	B-Application
,	O
and	O
macOS	B-Application
.	O
</s>
<s>
Oz	B-Language
contains	O
most	O
of	O
the	O
concepts	O
of	O
the	O
major	O
programming	O
paradigms	O
,	O
including	O
logic	B-Language
,	O
functional	B-Language
(	O
both	O
lazy	O
evaluation	O
and	O
eager	O
evaluation	O
)	O
,	O
imperative	B-Application
,	O
object-oriented	B-Language
,	O
constraint	B-Application
,	O
distributed	B-Architecture
,	O
and	O
concurrent	O
programming	O
.	O
</s>
<s>
Oz	B-Language
has	O
both	O
a	O
simple	O
formal	O
semantics	O
(	O
see	O
chapter	O
13	O
of	O
the	O
book	O
mentioned	O
below	O
)	O
and	O
Oz	B-Language
is	O
a	O
concurrency-oriented	O
language	O
,	O
as	O
the	O
term	O
was	O
introduced	O
by	O
Joe	O
Armstrong	O
,	O
the	O
main	O
designer	O
of	O
the	O
Erlang	B-Operating_System
language	I-Operating_System
.	O
</s>
<s>
A	O
concurrency-oriented	O
language	O
makes	O
concurrency	B-Operating_System
easy	O
to	O
use	O
and	O
efficient	O
.	O
</s>
<s>
Oz	B-Language
supports	O
a	O
canonical	O
graphical	B-Application
user	I-Application
interface	I-Application
(	O
GUI	B-Application
)	O
language	O
QTk	O
.	O
</s>
<s>
In	O
addition	O
to	O
multi-paradigm	O
programming	O
,	O
the	O
major	O
strengths	O
of	O
Oz	B-Language
are	O
in	O
constraint	B-Application
programming	I-Application
and	O
distributed	B-Architecture
programming	I-Architecture
.	O
</s>
<s>
Due	O
to	O
its	O
factored	O
design	O
,	O
Oz	B-Language
is	O
able	O
to	O
successfully	O
implement	O
a	O
network-transparent	O
distributed	B-Architecture
programming	I-Architecture
model	O
.	O
</s>
<s>
This	O
model	O
makes	O
it	O
easy	O
to	O
program	O
open	O
,	O
fault-tolerant	B-General_Concept
applications	O
within	O
the	O
language	O
.	O
</s>
<s>
For	O
constraint	B-Application
programming	I-Application
,	O
Oz	B-Language
introduces	O
the	O
idea	O
of	O
computation	O
spaces	O
,	O
which	O
allow	O
user-defined	O
search	O
and	O
distribution	O
strategies	O
orthogonal	O
to	O
the	O
constraint	B-Application
domain	O
.	O
</s>
<s>
Oz	B-Language
is	O
based	O
on	O
a	O
core	O
language	O
with	O
very	O
few	O
datatypes	O
that	O
can	O
be	O
extended	O
into	O
more	O
practical	O
ones	O
through	O
syntactic	O
sugar	O
.	O
</s>
<s>
Variable	O
names	O
in	O
Oz	B-Language
start	O
with	O
an	O
uppercase	O
letter	O
to	O
distinguish	O
them	O
from	O
literals	O
which	O
always	O
begin	O
with	O
a	O
lowercase	O
letter	O
.	O
</s>
<s>
Functions	O
are	O
first	O
class	O
values	O
,	O
allowing	O
higher	B-Application
order	I-Application
functional	I-Application
programming	O
:	O
</s>
<s>
Free	O
variable	O
values	O
are	O
found	O
using	O
static	O
lexical	B-Language
scoping	I-Language
.	O
</s>
<s>
Functions	O
are	O
like	O
other	O
Oz	B-Language
objects	O
.	O
</s>
<s>
Like	O
many	O
other	O
functional	B-Language
languages	I-Language
,	O
Oz	B-Language
supports	O
use	O
of	O
anonymous	B-General_Concept
functions	I-General_Concept
(	O
i.e.	O
</s>
<s>
functions	O
which	O
do	O
not	O
have	O
a	O
name	O
)	O
with	O
higher	B-Application
order	I-Application
programming	I-Application
.	O
</s>
<s>
Since	O
anonymous	B-General_Concept
functions	I-General_Concept
do	O
n't	O
have	O
names	O
,	O
it	O
is	O
not	O
possible	O
to	O
define	O
recursive	O
anonymous	B-General_Concept
functions	I-General_Concept
.	O
</s>
<s>
Functions	O
in	O
Oz	B-Language
are	O
supposed	O
to	O
return	O
a	O
value	O
at	O
the	O
last	O
statement	O
encountered	O
in	O
the	O
body	O
of	O
the	O
function	O
during	O
its	O
execution	O
.	O
</s>
<s>
But	O
Oz	B-Language
also	O
provides	O
a	O
facility	O
in	O
case	O
a	O
function	O
must	O
not	O
return	O
values	O
.	O
</s>
<s>
The	O
above	O
example	O
does	O
n't	O
return	O
any	O
value	O
,	O
it	O
just	O
prints	O
5	O
or	O
-5	O
in	O
the	O
Oz	B-Language
browser	O
depending	O
on	O
the	O
sign	O
of	O
X	O
.	O
</s>
<s>
This	O
example	O
computes	O
a	O
stream	O
of	O
prime	O
numbers	O
using	O
the	O
trial	B-Algorithm
division	I-Algorithm
algorithm	O
by	O
recursively	O
creating	O
concurrent	O
stream	O
agents	O
that	O
filter	O
out	O
non-prime	O
numbers	O
:	O
</s>
<s>
Oz	B-Language
uses	O
eager	O
evaluation	O
by	O
default	O
,	O
but	O
lazy	O
evaluation	O
is	O
possible	O
.	O
</s>
<s>
Lazy	O
evaluation	O
gives	O
the	O
possibility	O
of	O
storing	O
truly	O
infinite	O
data	O
structures	O
in	O
Oz	B-Language
.	O
</s>
<s>
The	O
declarative	O
concurrent	O
model	O
can	O
be	O
extended	O
with	O
message	B-Architecture
passing	I-Architecture
via	O
simple	O
semantics	O
:	O
</s>
<s>
It	O
is	O
again	O
possible	O
to	O
extend	O
the	O
declarative	O
model	O
to	O
support	O
state	O
and	O
object-oriented	B-Language
programming	I-Language
with	O
very	O
simple	O
semantics	O
.	O
</s>
<s>
With	O
these	O
simple	O
semantic	O
changes	O
,	O
the	O
whole	O
object-oriented	B-Language
paradigm	O
can	O
be	O
supported	O
.	O
</s>
<s>
With	O
a	O
little	O
syntactic	O
sugar	O
,	O
OOP	O
becomes	O
well	O
integrated	O
in	O
Oz	B-Language
.	O
</s>
<s>
The	O
execution	O
speed	O
of	O
a	O
program	O
produced	O
by	O
the	O
Mozart	O
compiler	O
(	O
version	O
1.4.0	O
implementing	O
Oz	B-Language
3	O
)	O
is	O
very	O
slow	O
.	O
</s>
<s>
On	O
a	O
2012	O
set	O
of	O
benchmarks	O
it	O
averaged	O
about	O
50	O
times	O
slower	O
than	O
that	O
of	O
the	O
GNU	B-Application
Compiler	I-Application
Collection	I-Application
(	O
GCC	B-Application
)	O
for	O
the	O
C	O
language	O
.	O
</s>
