<s>
Alice	B-Language
ML	I-Language
is	O
a	O
programming	O
language	O
designed	O
by	O
the	O
Programming	O
Systems	O
Laboratory	O
at	O
Saarland	O
University	O
,	O
Saarbrücken	O
,	O
Germany	O
.	O
</s>
<s>
It	O
is	O
a	O
dialect	O
of	O
Standard	B-Language
ML	I-Language
,	O
augmented	O
with	O
support	O
for	O
lazy	O
evaluation	O
,	O
concurrency	B-Operating_System
(	O
multithreading	B-Operating_System
and	O
distributed	B-Architecture
computing	I-Architecture
via	O
remote	B-Operating_System
procedure	I-Operating_System
calls	I-Operating_System
)	O
and	O
constraint	B-Application
programming	I-Application
.	O
</s>
<s>
Alice	B-Language
extends	O
Standard	B-Language
ML	I-Language
in	O
a	O
number	O
of	O
ways	O
that	O
distinguish	O
it	O
from	O
its	O
predecessor	O
.	O
</s>
<s>
Alice	B-Language
provides	O
concurrency	B-Operating_System
features	O
as	O
part	O
of	O
the	O
base	O
language	O
through	O
the	O
use	O
of	O
a	O
future	B-Operating_System
type	O
that	O
represents	O
a	O
value	O
being	O
provided	O
by	O
an	O
independent	O
thread	B-Operating_System
of	I-Operating_System
execution	I-Operating_System
.	O
</s>
<s>
A	O
thread	B-Operating_System
that	O
uses	O
a	O
future	B-Operating_System
value	O
will	O
block	O
on	O
an	O
attempt	O
to	O
access	O
the	O
value	O
until	O
the	O
thread	B-Operating_System
performing	O
it	O
has	O
completed	O
the	O
computation	O
.	O
</s>
<s>
A	O
related	O
concept	O
is	O
also	O
provided	O
termed	O
a	O
promise	B-Operating_System
,	O
allowing	O
a	O
thread	B-Operating_System
to	O
provide	O
a	O
future	B-Operating_System
value	O
that	O
it	O
will	O
compute	O
to	O
another	O
thread	B-Operating_System
.	O
</s>
<s>
Future	B-Operating_System
and	O
promise	B-Operating_System
typed	O
variables	O
are	O
used	O
to	O
implement	O
data-flow	O
synchronizing	O
.	O
</s>
<s>
Like	O
the	O
Haskell	B-Language
functional	B-Language
language	I-Language
,	O
Alice	B-Language
provides	O
facilities	O
to	O
allow	O
a	O
lazy	O
evaluation	O
strategy	O
in	O
programs	O
,	O
unlike	O
the	O
traditional	O
eager	O
evaluation	O
strategy	O
of	O
Standard	B-Language
ML	I-Language
.	O
</s>
<s>
While	O
Haskell	B-Language
uses	O
the	O
lazy	O
model	O
by	O
default	O
,	O
Alice	B-Language
uses	O
an	O
eager	O
evaluation	O
model	O
by	O
default	O
,	O
needing	O
an	O
explicit	O
programming	O
statement	O
for	O
a	O
computation	O
to	O
evaluate	O
lazily	O
.	O
</s>
<s>
The	O
Alice	B-Language
implementation	O
from	O
Saarland	O
University	O
uses	O
the	O
Simple	O
Extensible	O
Abstract	O
Machine	O
(	O
SEAM	O
)	O
virtual	B-Architecture
machine	I-Architecture
.	O
</s>
<s>
It	O
is	O
free	B-Application
software	I-Application
,	O
and	O
features	O
just-in-time	O
compilation	O
to	O
bytecode	O
and	O
native	B-Language
code	I-Language
for	O
the	O
x86	B-Operating_System
architecture	I-Operating_System
.	O
</s>
<s>
Early	O
versions	O
of	O
Alice	B-Language
ran	O
on	O
the	O
Mozart	B-Language
Programming	I-Language
System	I-Language
(	O
Oz	B-Language
)	O
virtual	B-Architecture
machine	I-Architecture
(	O
VM	O
)	O
,	O
allowing	O
interfacing	O
between	O
Alice	B-Language
and	O
Oz	B-Language
code	O
.	O
</s>
<s>
Alice	B-Language
's	O
remote	O
procedure	O
calling	O
depends	O
on	O
the	O
virtual	B-Architecture
machine	I-Architecture
,	O
because	O
it	O
may	O
send	O
code	O
to	O
be	O
computed	O
from	O
one	O
computer	O
to	O
another	O
.	O
</s>
<s>
Alice	B-Language
extends	O
Standard	B-Language
ML	I-Language
with	O
several	O
primitives	O
for	O
lazy	O
evaluation	O
and	O
concurrency	B-Operating_System
.	O
</s>
<s>
For	O
example	O
,	O
threads	B-Operating_System
may	O
be	O
created	O
using	O
the	O
spawn	O
keyword	O
.	O
</s>
<s>
The	O
variable	O
x	O
is	O
now	O
bound	O
to	O
a	O
so-called	O
future	B-Operating_System
.	O
</s>
<s>
When	O
an	O
operation	O
requires	O
the	O
value	O
of	O
x	O
,	O
it	O
blocks	O
until	O
the	O
thread	B-Operating_System
is	O
done	O
with	O
the	O
computation	O
.	O
</s>
