<s>
SequenceL	B-Operating_System
is	O
a	O
general	O
purpose	O
functional	B-Language
programming	I-Language
language	I-Language
and	O
auto-parallelizing	O
(	O
Parallel	B-Operating_System
computing	I-Operating_System
)	O
compiler	B-Language
and	O
tool	O
set	O
,	O
whose	O
primary	O
design	O
objectives	O
are	O
performance	O
on	O
multi-core	B-Architecture
processor	I-Architecture
hardware	O
,	O
ease	O
of	O
programming	O
,	O
platform	O
portability/optimization	O
,	O
and	O
code	O
clarity	O
and	O
readability	O
.	O
</s>
<s>
Its	O
main	O
advantage	O
is	O
that	O
it	O
can	O
be	O
used	O
to	O
write	O
straightforward	O
code	O
that	O
automatically	O
takes	O
full	O
advantage	O
of	O
all	O
the	O
processing	O
power	B-Device
available	O
,	O
without	O
programmers	B-Application
needing	O
to	O
be	O
concerned	O
with	O
identifying	O
parallelisms	B-Operating_System
,	O
specifying	O
vectorization	B-General_Concept
,	O
avoiding	O
race	B-Operating_System
conditions	I-Operating_System
,	O
and	O
other	O
challenges	O
of	O
manual	O
directive-based	O
programming	O
approaches	O
such	O
as	O
OpenMP	B-Application
.	O
</s>
<s>
Programs	O
written	O
in	O
SequenceL	B-Operating_System
can	O
be	O
compiled	B-Language
to	O
multithreaded	B-Operating_System
code	O
that	O
runs	O
in	O
parallel	O
,	O
with	O
no	O
explicit	O
indications	O
from	O
a	O
programmer	B-Application
of	O
how	O
or	O
what	O
to	O
parallelize	O
.	O
</s>
<s>
,	O
versions	O
of	O
the	O
SequenceL	B-Operating_System
compiler	B-Language
generate	O
parallel	B-Operating_System
code	I-Operating_System
in	O
C++	B-Language
and	O
OpenCL	B-Application
,	O
which	O
allows	O
it	O
to	O
work	O
with	O
most	O
popular	O
programming	O
languages	O
,	O
including	O
C	B-Language
,	O
C++	B-Language
,	O
C#	B-Application
,	O
Fortran	B-Application
,	O
Java	B-Language
,	O
and	O
Python	B-Language
.	O
</s>
<s>
A	O
platform-specific	O
runtime	O
manages	O
the	O
threads	B-Operating_System
safely	O
,	O
automatically	O
providing	O
parallel	O
performance	O
according	O
to	O
the	O
number	O
of	O
cores	O
available	O
,	O
currently	O
supporting	O
x86	B-Operating_System
,	O
POWER8	B-Device
,	O
and	O
ARM	B-Architecture
platforms	O
.	O
</s>
<s>
SequenceL	B-Operating_System
was	O
initially	O
developed	O
over	O
a	O
20-year	O
period	O
starting	O
in	O
1989	O
,	O
mostly	O
at	O
Texas	O
Tech	O
University	O
.	O
</s>
<s>
The	O
goal	O
of	O
creating	O
a	O
language	O
that	O
was	O
simple	O
enough	O
to	O
be	O
readable	O
,	O
but	O
unambiguous	O
enough	O
to	O
be	O
executable	O
,	O
drove	O
the	O
inventors	O
to	O
settle	O
on	O
a	O
functional	B-Language
,	O
declarative	B-Language
language	I-Language
approach	O
,	O
where	O
a	O
programmer	B-Application
describes	O
desired	O
results	O
,	O
rather	O
than	O
the	O
means	O
to	O
achieve	O
them	O
.	O
</s>
<s>
In	O
1998	O
,	O
research	O
began	O
to	O
apply	O
SequenceL	B-Operating_System
to	O
parallel	B-Operating_System
computing	I-Operating_System
.	O
</s>
<s>
This	O
culminated	O
in	O
2004	O
when	O
it	O
took	O
its	O
more	O
complete	O
form	O
with	O
the	O
addition	O
of	O
the	O
normalize-transpose	O
(	O
NT	O
)	O
semantic	O
,	O
which	O
coincided	O
with	O
the	O
major	O
vendors	O
of	O
central	B-General_Concept
processing	I-General_Concept
units	I-General_Concept
(	O
CPUs	O
)	O
making	O
a	O
major	O
shift	O
to	O
multi-core	B-Architecture
processors	I-Architecture
rather	O
than	O
continuing	O
to	O
increase	O
clock	O
speeds	O
.	O
</s>
<s>
NT	O
is	O
the	O
semantic	O
work-horse	O
,	O
being	O
used	O
to	O
simplify	O
and	O
decompose	O
structures	O
,	O
based	O
on	O
a	O
dataflow-like	O
execution	O
strategy	O
similar	O
to	O
GAMMA	O
and	O
NESL	O
.	O
</s>
<s>
Though	O
it	O
was	O
not	O
the	O
original	O
intent	O
,	O
these	O
new	O
approaches	O
allowed	O
the	O
language	O
to	O
parallelize	O
a	O
large	O
fraction	O
of	O
the	O
operations	O
it	O
performed	O
,	O
transparently	O
to	O
the	O
programmer	B-Application
.	O
</s>
<s>
In	O
2006	O
,	O
a	O
prototype	O
auto-parallelizing	O
compiler	B-Language
was	O
developed	O
at	O
Texas	O
Tech	O
University	O
.	O
</s>
<s>
In	O
2009	O
,	O
Texas	O
Tech	O
licensed	O
the	O
intellectual	O
property	O
to	O
Texas	O
Multicore	B-Architecture
Technologies	O
(	O
TMT	O
)	O
,	O
for	O
follow-on	O
commercial	O
development	O
.	O
</s>
<s>
SequenceL	B-Operating_System
is	O
designed	O
to	O
be	O
as	O
simple	O
as	O
possible	O
to	O
learn	O
and	O
use	O
,	O
focusing	O
on	O
algorithmic	O
code	O
where	O
it	O
adds	O
value	O
,	O
e.g.	O
,	O
the	O
inventors	O
chose	O
not	O
to	O
reinvent	O
I/O	B-General_Concept
since	O
C	B-Language
handled	O
that	O
well	O
.	O
</s>
<s>
SequenceL	B-Operating_System
is	O
strictly	O
evaluated	O
(	O
like	O
Lisp	B-Language
)	O
,	O
statically	O
typed	O
with	O
type	O
inference	O
(	O
like	O
Haskell	B-Language
)	O
,	O
and	O
uses	O
a	O
combination	O
of	O
infix	O
and	O
prefix	O
operators	O
that	O
resemble	O
standard	O
,	O
informal	O
mathematical	O
notation	O
(	O
like	O
C	B-Language
,	O
Pascal	B-Application
,	O
Python	B-Language
,	O
etc	O
.	O
)	O
.	O
</s>
<s>
It	O
is	O
a	O
purely	O
declarative	B-Language
language	I-Language
,	O
meaning	O
that	O
a	O
programmer	B-Application
defines	O
functions	O
,	O
in	O
the	O
mathematical	O
sense	O
,	O
without	O
giving	O
instructions	O
for	O
their	O
implementation	O
.	O
</s>
<s>
The	O
SequenceL	B-Operating_System
definition	O
mirrors	O
that	O
definition	O
more	O
or	O
less	O
exactly	O
:	O
</s>
<s>
From	O
this	O
formal	O
definition	O
,	O
SequenceL	B-Operating_System
infers	O
the	O
dimensions	O
of	O
the	O
defined	O
product	O
from	O
the	O
formula	O
for	O
its	O
(	O
i	O
,	O
j	O
)	O
'	O
th	O
entry	O
(	O
as	O
the	O
set	O
of	O
pairs	O
(	O
i	O
,	O
j	O
)	O
for	O
which	O
the	O
right	O
hand	O
side	O
is	O
defined	O
)	O
and	O
computes	O
each	O
entry	O
by	O
the	O
same	O
formula	O
as	O
in	O
the	O
informal	O
definition	O
above	O
.	O
</s>
<s>
Because	O
of	O
this	O
,	O
the	O
SequenceL	B-Operating_System
compiler	B-Language
can	O
perform	O
operations	O
in	O
any	O
order	O
(	O
including	O
parallel	O
order	O
)	O
which	O
satisfies	O
the	O
defining	O
equation	O
.	O
</s>
<s>
In	O
this	O
example	O
,	O
computation	O
of	O
coordinates	O
in	O
the	O
product	O
will	O
be	O
parallelized	B-Operating_System
in	O
a	O
way	O
that	O
,	O
for	O
large	O
matrices	O
,	O
scales	O
linearly	O
with	O
the	O
number	O
of	O
processors	O
.	O
</s>
<s>
As	O
noted	O
above	O
,	O
SequenceL	B-Operating_System
has	O
no	O
built-in	O
constructs	O
for	O
input/output	B-General_Concept
(	O
I/O	B-General_Concept
)	O
since	O
it	O
was	O
designed	O
to	O
work	O
in	O
an	O
additive	O
manner	O
with	O
other	O
programming	O
languages	O
.	O
</s>
<s>
The	O
decision	O
to	O
compile	B-Language
to	O
multithreaded	B-Operating_System
C++	B-Language
and	O
support	O
the	O
20+	O
Simplified	B-Application
Wrapper	I-Application
and	I-Application
Interface	I-Application
Generator	I-Application
(	O
SWIG	B-Application
)	O
languages	O
(	O
C	B-Language
,	O
C++	B-Language
,	O
C#	B-Application
,	O
Java	B-Language
,	O
Python	B-Language
,	O
etc	O
.	O
)	O
</s>
<s>
It	O
can	O
be	O
used	O
to	O
enhance	O
extant	O
applications	O
,	O
create	O
multicore	B-Architecture
libraries	O
,	O
and	O
even	O
create	O
standalone	O
applications	O
by	O
linking	O
the	O
resulting	O
code	O
with	O
other	O
code	O
which	O
performs	O
I/O	B-General_Concept
tasks	O
.	O
</s>
<s>
SequenceL	B-Operating_System
functions	O
can	O
also	O
be	O
queried	O
from	O
an	O
interpreter	B-Application
with	O
given	O
inputs	O
,	O
like	O
Python	B-Language
and	O
other	O
interpreted	B-Application
languages	I-Application
.	O
</s>
<s>
The	O
main	O
non-scalar	O
construct	O
of	O
SequenceL	B-Operating_System
is	O
the	O
sequence	O
,	O
which	O
is	O
essentially	O
a	O
list	O
.	O
</s>
<s>
To	O
avoid	O
the	O
routine	O
use	O
of	O
recursion	O
common	O
in	O
many	O
purely	B-Application
functional	I-Application
languages	O
,	O
SequenceL	B-Operating_System
uses	O
a	O
technique	O
termed	O
normalize	O
–	O
transpose	O
(	O
NT	O
)	O
,	O
in	O
which	O
scalar	O
operations	O
are	O
automatically	O
distributed	O
over	O
elements	O
of	O
a	O
sequence	O
.	O
</s>
<s>
SequenceL	B-Operating_System
allows	O
this	O
problem	O
to	O
be	O
programmed	O
by	O
literally	O
transcribing	O
the	O
above	O
definition	O
into	O
the	O
language	O
.	O
</s>
<s>
In	O
SequenceL	B-Operating_System
,	O
a	O
sequence	O
of	O
the	O
numbers	O
from	O
2	O
through	O
z-1	O
,	O
inclusive	O
,	O
is	O
just	O
2	O
...	O
)	O
,	O
so	O
a	O
program	O
to	O
find	O
all	O
of	O
the	O
primes	O
between	O
100	O
and	O
200	O
can	O
be	O
written	O
:	O
</s>
<s>
Rather	O
,	O
a	O
programmer	B-Application
will	O
typically	O
pass	O
that	O
part	O
in	O
as	O
the	O
argument	O
.	O
</s>
<s>
Since	O
the	O
program	O
expects	O
a	O
scalar	O
as	O
an	O
argument	O
,	O
passing	O
it	O
a	O
sequence	O
of	O
numbers	O
instead	O
will	O
cause	O
SequenceL	B-Operating_System
to	O
perform	O
the	O
operation	O
on	O
each	O
member	O
of	O
the	O
sequence	O
automatically	O
.	O
</s>
<s>
In	O
addition	O
to	O
solving	O
this	O
problem	O
with	O
a	O
very	O
short	O
and	O
readable	O
program	O
,	O
SequenceL	B-Operating_System
’s	O
evaluation	O
of	O
the	O
nested	O
sequences	O
would	O
all	O
be	O
performed	O
in	O
parallel	O
.	O
</s>
<s>
The	O
following	O
software	O
components	O
are	O
available	O
and	O
supported	O
by	O
TMT	O
for	O
use	O
in	O
writing	O
SequenceL	B-Operating_System
code	O
.	O
</s>
<s>
All	O
components	O
are	O
available	O
on	O
x86	B-Operating_System
platforms	O
running	O
Windows	B-Application
,	O
macOS	B-Application
,	O
and	O
most	O
varieties	O
of	O
Linux	B-Application
(	O
including	O
CentOS	O
,	O
RedHat	O
,	O
OpenSUSE	B-Operating_System
,	O
and	O
Ubuntu	B-Operating_System
)	O
,	O
and	O
on	O
ARM	B-Architecture
and	O
IBM	B-Device
Power	I-Device
platforms	O
running	O
most	O
varieties	O
of	O
Linux	B-Application
.	O
</s>
<s>
A	O
command-line	B-Application
interpreter	B-Application
allows	O
writing	O
code	O
directly	O
into	O
a	O
command	O
shell	O
,	O
or	O
loading	O
code	O
from	O
prewritten	O
text	O
files	O
.	O
</s>
<s>
It	O
is	O
also	O
available	O
via	O
the	O
popular	O
Eclipse	B-Application
integrated	B-Application
development	I-Application
environment	I-Application
(	O
IDE	O
)	O
.	O
</s>
<s>
Code	O
executed	O
in	O
the	O
interpreter	B-Application
does	O
not	O
run	O
in	O
parallel	O
;	O
it	O
executes	O
in	O
one	O
thread	B-Operating_System
.	O
</s>
<s>
A	O
command-line	B-Application
compiler	B-Language
reads	O
SequenceL	B-Operating_System
code	O
and	O
generates	O
highly	O
parallelized	B-Operating_System
,	O
vectorized	B-General_Concept
,	O
C++	B-Language
,	O
and	O
optionally	O
OpenCL	B-Application
,	O
which	O
must	O
be	O
linked	O
with	O
the	O
SequenceL	B-Operating_System
runtime	O
library	O
to	O
execute	O
.	O
</s>
<s>
The	O
runtime	O
environment	O
is	O
a	O
pre-compiled	O
set	O
of	O
libraries	O
which	O
works	O
with	O
the	O
compiled	B-Language
parallelized	B-Operating_System
C++	B-Language
code	I-Language
to	O
execute	O
optimally	O
on	O
the	O
target	O
platform	O
.	O
</s>
<s>
An	O
Eclipse	B-Application
integrated	B-Application
development	I-Application
environment	I-Application
plug-in	B-Application
provides	O
standard	O
editing	O
abilities	O
(	O
function	O
rollup	O
,	O
chromacoding	O
,	O
etc	O
.	O
</s>
<s>
)	O
,	O
and	O
a	O
SequenceL	B-Operating_System
debugging	O
environment	O
.	O
</s>
<s>
This	O
plug-in	B-Application
runs	O
against	O
the	O
SequenceL	B-Operating_System
Interpreter	B-Application
,	O
so	O
cannot	O
be	O
used	O
to	O
debug	O
the	O
multithreaded	B-Operating_System
code	O
;	O
however	O
,	O
by	O
providing	O
automatic	O
parallelization	B-Operating_System
,	O
debugging	O
of	O
parallel	O
SequenceL	B-Operating_System
code	O
is	O
really	O
verifying	O
correctness	O
of	O
sequential	O
SequenceL	B-Operating_System
code	O
.	O
</s>
<s>
That	O
is	O
,	O
if	O
it	O
runs	O
correctly	O
sequentially	O
,	O
it	O
should	O
run	O
correctly	O
in	O
parallel	O
–	O
so	O
debugging	O
in	O
the	O
interpreter	B-Application
is	O
sufficient	O
.	O
</s>
<s>
Various	O
math	O
and	O
other	O
standard	O
function	O
libraries	O
are	O
included	O
as	O
SequenceL	B-Operating_System
source	O
code	O
to	O
streamline	O
the	O
programming	O
process	O
and	O
serve	O
as	O
best	O
practice	O
examples	O
.	O
</s>
<s>
These	O
may	O
be	O
imported	O
,	O
in	O
much	O
the	O
same	O
way	O
that	O
C	B-Language
or	O
C++	B-Language
libraries	O
are	O
#included	O
.	O
</s>
