<s>
APL	B-General_Concept
(	O
named	O
after	O
the	O
book	O
A	O
Programming	O
Language	O
)	O
is	O
a	O
programming	O
language	O
developed	O
in	O
the	O
1960s	O
by	O
Kenneth	O
E	O
.	O
Iverson	O
.	O
</s>
<s>
Its	O
central	O
datatype	O
is	O
the	O
multidimensional	O
array	B-Application
.	O
</s>
<s>
It	O
uses	O
a	O
large	O
range	O
of	O
special	B-Language
graphic	I-Language
symbols	I-Language
to	O
represent	O
most	O
functions	O
and	O
operators	B-Language
,	O
leading	O
to	O
very	O
concise	O
code	O
.	O
</s>
<s>
It	O
has	O
been	O
an	O
important	O
influence	O
on	O
the	O
development	O
of	O
concept	O
modeling	O
,	O
spreadsheets	B-Application
,	O
functional	B-Language
programming	I-Language
,	O
and	O
computer	O
math	O
packages	O
.	O
</s>
<s>
This	O
notation	O
was	O
used	O
inside	O
IBM	O
for	O
short	O
research	O
reports	O
on	O
computer	O
systems	O
,	O
such	O
as	O
the	O
Burroughs	B-Device
B5000	I-Device
and	O
its	O
stack	O
mechanism	O
when	O
stack	B-Application
machines	I-Application
versus	O
register	B-Application
machines	I-Application
were	O
being	O
evaluated	O
by	O
IBM	O
for	O
upcoming	O
computers	O
.	O
</s>
<s>
In	O
1979	O
,	O
Iverson	O
received	O
the	O
Turing	O
Award	O
for	O
his	O
work	O
on	O
APL	B-General_Concept
.	O
</s>
<s>
As	O
early	O
as	O
1962	O
,	O
the	O
first	O
attempt	O
to	O
use	O
the	O
notation	O
to	O
describe	O
a	O
complete	O
computer	O
system	O
happened	O
after	O
Falkoff	O
discussed	O
with	O
William	O
C	O
.	O
Carter	O
his	O
work	O
to	O
standardize	O
the	O
instruction	O
set	O
for	O
the	O
machines	O
that	O
later	O
became	O
the	O
IBM	B-Application
System/360	I-Application
family	O
.	O
</s>
<s>
In	O
1963	O
,	O
Herbert	O
Hellerman	O
,	O
working	O
at	O
the	O
IBM	O
Systems	O
Research	O
Institute	O
,	O
implemented	O
a	O
part	O
of	O
the	O
notation	O
on	O
an	O
IBM	B-Device
1620	I-Device
computer	O
,	O
and	O
it	O
was	O
used	O
by	O
students	O
in	O
a	O
special	O
high	O
school	O
course	O
on	O
calculating	O
transcendental	O
functions	O
by	O
series	O
summation	O
.	O
</s>
<s>
Students	O
tested	O
their	O
code	O
in	O
Hellerman	O
's	O
lab	O
.	O
</s>
<s>
This	O
implementation	O
of	O
a	O
part	O
of	O
the	O
notation	O
was	O
called	O
Personalized	O
Array	B-Application
Translator	O
(	O
PAT	O
)	O
.	O
</s>
<s>
In	O
1963	O
,	O
Falkoff	O
,	O
Iverson	O
,	O
and	O
Edward	O
H	O
.	O
Sussenguth	O
Jr.	O
,	O
all	O
working	O
at	O
IBM	O
,	O
used	O
the	O
notation	O
for	O
a	O
formal	O
description	O
of	O
the	O
IBM	B-Application
System/360	I-Application
series	O
machine	O
architecture	O
and	O
functionality	O
,	O
which	O
resulted	O
in	O
a	O
paper	O
published	O
in	O
IBM	O
Systems	O
Journal	O
in	O
1964	O
.	O
</s>
<s>
After	O
Lawrence	O
M	O
.	O
Breed	O
and	O
Philip	O
S	B-Language
.	O
Abrams	O
of	O
Stanford	O
University	O
joined	O
the	O
team	O
at	O
IBM	O
Research	O
,	O
they	O
continued	O
their	O
prior	O
work	O
on	O
an	O
implementation	O
programmed	O
in	O
FORTRAN	B-Application
IV	O
for	O
a	O
part	O
of	O
the	O
notation	O
which	O
had	O
been	O
done	O
for	O
the	O
IBM	B-Device
7090	I-Device
computer	O
running	O
on	O
the	O
IBSYS	B-Operating_System
operating	O
system	O
.	O
</s>
<s>
The	O
basis	O
of	O
this	O
implementation	O
was	O
described	O
in	O
detail	O
by	O
Abrams	O
in	O
a	O
Stanford	O
University	O
Technical	O
Report	O
,	O
"	O
An	O
Interpreter	B-Application
for	O
Iverson	O
Notation	O
"	O
in	O
1966	O
,	O
the	O
academic	O
aspect	O
of	O
this	O
was	O
formally	O
supervised	O
by	O
Niklaus	O
Wirth	O
.	O
</s>
<s>
Like	O
Hellerman	O
's	O
PAT	O
system	O
earlier	O
,	O
this	O
implementation	O
did	O
not	O
include	O
the	O
APL	B-General_Concept
character	B-General_Concept
set	I-General_Concept
but	O
used	O
special	O
English	O
reserved	O
words	O
for	O
functions	O
and	O
operators	B-Language
.	O
</s>
<s>
The	O
system	O
was	O
later	O
adapted	O
for	O
a	O
time-sharing	B-General_Concept
system	I-General_Concept
and	O
,	O
by	O
November	O
1966	O
,	O
it	O
had	O
been	O
reprogrammed	O
for	O
the	O
IBM	B-Device
System/360	I-Device
Model	I-Device
50	I-Device
computer	O
running	O
in	O
a	O
time-sharing	B-General_Concept
mode	O
and	O
was	O
used	O
internally	O
at	O
IBM	O
.	O
</s>
<s>
A	O
key	O
development	O
in	O
the	O
ability	O
to	O
use	O
APL	B-General_Concept
effectively	O
,	O
before	O
the	O
wide	O
use	O
of	O
cathode	O
ray	O
tube	O
(	O
CRT	O
)	O
terminals	O
,	O
was	O
the	O
development	O
of	O
a	O
special	O
IBM	O
Selectric	O
typewriter	O
interchangeable	O
typing	O
element	O
with	O
all	O
the	O
special	O
APL	B-General_Concept
characters	O
on	O
it	O
.	O
</s>
<s>
This	O
was	O
used	O
on	O
paper	O
printing	O
terminal	O
workstations	O
using	O
the	O
Selectric	O
typewriter	O
and	O
typing	O
element	O
mechanism	O
,	O
such	O
as	O
the	O
IBM	B-Device
1050	I-Device
and	O
IBM	O
2741	O
terminal	O
.	O
</s>
<s>
Keycaps	O
could	O
be	O
placed	O
over	O
the	O
normal	O
keys	O
to	O
show	O
which	O
APL	B-General_Concept
characters	O
would	O
be	O
entered	O
and	O
typed	O
when	O
that	O
key	O
was	O
struck	O
.	O
</s>
<s>
For	O
the	O
first	O
time	O
,	O
a	O
programmer	B-Application
could	O
type	O
in	O
and	O
see	O
proper	O
APL	B-General_Concept
characters	O
as	O
used	O
in	O
Iverson	O
's	O
notation	O
and	O
not	O
be	O
forced	O
to	O
use	O
awkward	O
English	O
keyword	O
representations	O
of	O
them	O
.	O
</s>
<s>
Falkoff	O
and	O
Iverson	O
had	O
the	O
special	O
APL	B-General_Concept
Selectric	O
typing	O
elements	O
,	O
987	O
and	O
988	O
,	O
designed	O
in	O
late	O
1964	O
,	O
although	O
no	O
APL	B-General_Concept
computer	O
system	O
was	O
available	O
to	O
use	O
them	O
.	O
</s>
<s>
Iverson	O
cited	O
Falkoff	O
as	O
the	O
inspiration	O
for	O
the	O
idea	O
of	O
using	O
an	O
IBM	O
Selectric	O
typing	O
element	O
for	O
the	O
APL	B-General_Concept
character	B-General_Concept
set	I-General_Concept
.	O
</s>
<s>
Many	O
APL	B-Language
symbols	I-Language
,	O
even	O
with	O
the	O
APL	B-General_Concept
characters	O
on	O
the	O
Selectric	O
typing	O
element	O
,	O
still	O
had	O
to	O
be	O
typed	O
in	O
by	O
over-striking	O
two	O
extant	O
element	O
characters	O
.	O
</s>
<s>
This	O
was	O
necessary	O
because	O
the	O
APL	B-General_Concept
character	B-General_Concept
set	I-General_Concept
was	O
much	O
larger	O
than	O
the	O
88	O
characters	O
allowed	O
on	O
the	O
typing	O
element	O
,	O
even	O
when	O
letters	O
were	O
restricted	O
to	O
upper-case	O
(	O
capitals	O
)	O
.	O
</s>
<s>
The	O
first	O
APL	B-General_Concept
interactive	O
login	O
and	O
creation	O
of	O
an	O
APL	B-General_Concept
workspace	O
was	O
in	O
1966	O
by	O
Larry	O
Breed	O
using	O
an	O
IBM	B-Device
1050	I-Device
terminal	O
at	O
the	O
IBM	O
Mohansic	O
Labs	O
near	O
Thomas	O
J	B-Language
.	O
Watson	O
Research	O
Center	O
,	O
the	O
home	O
of	O
APL	B-General_Concept
,	O
in	O
Yorktown	O
Heights	O
,	O
New	O
York	O
.	O
</s>
<s>
IBM	O
was	O
chiefly	O
responsible	O
for	O
introducing	O
APL	B-General_Concept
to	O
the	O
marketplace	O
.	O
</s>
<s>
The	O
first	O
publicly	O
available	O
version	O
of	O
APL	B-General_Concept
was	O
released	O
in	O
1968	O
for	O
the	O
IBM	B-Device
1130	I-Device
.	O
</s>
<s>
IBM	O
provided	O
APL	B-General_Concept
\1130	O
for	O
free	O
but	O
without	O
liability	O
or	O
support	O
.	O
</s>
<s>
APL	B-General_Concept
gained	O
its	O
foothold	O
on	O
mainframe	O
timesharing	B-General_Concept
systems	O
from	O
the	O
late	O
1960s	O
through	O
the	O
early	O
1980s	O
,	O
in	O
part	O
because	O
it	O
would	O
support	O
multiple	O
users	O
on	O
lower-specification	O
systems	O
that	O
had	O
no	O
dynamic	B-General_Concept
address	I-General_Concept
translation	I-General_Concept
hardware	O
.	O
</s>
<s>
Additional	O
improvements	O
in	O
performance	O
for	O
selected	O
IBM	B-Device
System/370	I-Device
mainframe	O
systems	O
included	O
the	O
APL	B-General_Concept
Assist	O
Microcode	O
in	O
which	O
some	O
support	O
for	O
APL	B-General_Concept
execution	O
was	O
included	O
in	O
the	O
processor	O
's	O
firmware	B-Application
,	O
as	O
distinct	O
from	O
being	O
implemented	O
entirely	O
by	O
higher-level	O
software	O
.	O
</s>
<s>
Somewhat	O
later	O
,	O
as	O
suitably	O
performing	O
hardware	O
was	O
finally	O
growing	O
available	O
in	O
the	O
mid	O
-	O
to	O
late-1980s	O
,	O
many	O
users	O
migrated	O
their	O
applications	O
to	O
the	O
personal	B-Device
computer	I-Device
environment	O
.	O
</s>
<s>
Early	O
IBM	O
APL	B-General_Concept
interpreters	B-Application
for	O
IBM	B-Application
360	I-Application
and	O
IBM	B-Device
370	I-Device
hardware	O
implemented	O
their	O
own	O
multi-user	O
management	O
instead	O
of	O
relying	O
on	O
the	O
host	O
services	O
,	O
thus	O
they	O
were	O
their	O
own	O
timesharing	B-General_Concept
systems	O
.	O
</s>
<s>
First	O
introduced	O
for	O
use	O
at	O
IBM	O
in	O
1966	O
,	O
the	O
APL	B-General_Concept
\360	O
system	O
was	O
a	O
multi-user	O
interpreter	B-Application
.	O
</s>
<s>
The	O
ability	O
to	O
programmatically	O
communicate	O
with	O
the	O
operating	O
system	O
for	O
information	O
and	O
setting	O
interpreter	B-Application
system	O
variables	O
was	O
done	O
through	O
special	O
privileged	O
"	O
I-beam	O
"	O
functions	O
,	O
using	O
both	O
monadic	O
and	O
dyadic	O
operations	O
.	O
</s>
<s>
In	O
1973	O
,	O
IBM	O
released	O
APL.SV	O
,	O
which	O
was	O
a	O
continuation	O
of	O
the	O
same	O
product	O
,	O
but	O
which	O
offered	O
shared	B-Language
variables	I-Language
as	O
a	O
means	O
to	O
access	O
facilities	O
outside	O
of	O
the	O
APL	B-General_Concept
system	O
,	O
such	O
as	O
operating	O
system	O
files	O
.	O
</s>
<s>
In	O
the	O
mid-1970s	O
,	O
the	O
IBM	O
mainframe	O
interpreter	B-Application
was	O
even	O
adapted	O
for	O
use	O
on	O
the	O
IBM	B-Device
5100	I-Device
desktop	O
computer	O
,	O
which	O
had	O
a	O
small	O
CRT	O
and	O
an	O
APL	B-General_Concept
keyboard	B-Device
,	O
when	O
most	O
other	O
small	O
computers	O
of	O
the	O
time	O
only	O
offered	O
BASIC	O
.	O
</s>
<s>
In	O
the	O
1980s	O
,	O
the	O
VSAPL	O
program	O
product	O
enjoyed	O
wide	O
use	O
with	O
Conversational	B-Operating_System
Monitor	I-Operating_System
System	I-Operating_System
(	O
CMS	B-Operating_System
)	O
,	O
Time	B-Application
Sharing	I-Application
Option	I-Application
(	O
TSO	B-Application
)	O
,	O
VSPC	O
,	O
MUSIC/SP	B-Application
,	O
and	O
CICS	B-Application
users	O
.	O
</s>
<s>
In	O
1973	O
–	O
1974	O
,	O
Patrick	O
E	O
.	O
Hagerty	O
directed	O
the	O
implementation	O
of	O
the	O
University	O
of	O
Maryland	O
APL	B-General_Concept
interpreter	B-Application
for	O
the	O
1100	O
line	O
of	O
the	O
Sperry	O
UNIVAC	B-Device
1100/2200	I-Device
series	I-Device
mainframe	O
computers	O
.	O
</s>
<s>
Xerox	O
APL	B-General_Concept
was	O
available	O
from	O
June	O
1975	O
for	O
Xerox	O
560	O
and	O
Sigma	O
6	O
,	O
7	O
,	O
and	O
9	O
mainframes	O
running	O
CP-V	O
and	O
for	O
Honeywell	B-Operating_System
CP-6	I-Operating_System
.	O
</s>
<s>
In	O
the	O
1960s	O
and	O
1970s	O
,	O
several	O
timesharing	B-General_Concept
firms	O
arose	O
that	O
sold	O
APL	B-General_Concept
services	O
using	O
modified	O
versions	O
of	O
the	O
IBM	O
APL	B-General_Concept
\360	O
interpreter	B-Application
.	O
</s>
<s>
In	O
North	O
America	O
,	O
the	O
better-known	O
ones	O
were	O
IP	O
Sharp	O
Associates	O
,	O
Scientific	O
Time	B-General_Concept
Sharing	I-General_Concept
Corporation	O
(	O
STSC	O
)	O
,	O
Time	B-General_Concept
Sharing	I-General_Concept
Resources	O
(	O
TSR	O
)	O
,	O
and	O
The	O
Computer	O
Company	O
(	O
TCC	O
)	O
.	O
</s>
<s>
CompuServe	O
also	O
entered	O
the	O
market	O
in	O
1978	O
with	O
an	O
APL	B-General_Concept
Interpreter	B-Application
based	O
on	O
a	O
modified	O
version	O
of	O
Digital	O
Equipment	O
Corp	O
and	O
Carnegie	O
Mellon	O
's	O
,	O
which	O
ran	O
on	O
DEC	O
's	O
KI	O
and	O
KL	O
36-bit	O
machines	O
.	O
</s>
<s>
CompuServe	O
's	O
APL	B-General_Concept
was	O
available	O
both	O
to	O
its	O
commercial	O
market	O
and	O
the	O
consumer	O
information	O
service	O
.	O
</s>
<s>
With	O
the	O
advent	O
first	O
of	O
less	O
expensive	O
mainframes	O
such	O
as	O
the	O
IBM	B-Device
4300	I-Device
,	O
and	O
later	O
the	O
personal	B-Device
computer	I-Device
,	O
by	O
the	O
mid-1980s	O
,	O
the	O
timesharing	B-General_Concept
industry	O
was	O
all	O
but	O
gone	O
.	O
</s>
<s>
Sharp	O
APL	B-General_Concept
was	O
available	O
from	O
IP	O
Sharp	O
Associates	O
,	O
first	O
as	O
a	O
timesharing	B-General_Concept
service	O
in	O
the	O
1960s	O
,	O
and	O
later	O
as	O
a	O
program	O
product	O
starting	O
around	O
1979	O
.	O
</s>
<s>
Sharp	O
APL	B-General_Concept
was	O
an	O
advanced	O
APL	B-General_Concept
implementation	O
with	O
many	O
language	O
extensions	O
,	O
such	O
as	O
packages	O
(	O
the	O
ability	O
to	O
put	O
one	O
or	O
more	O
objects	O
into	O
a	O
single	O
variable	O
)	O
,	O
file	O
system	O
,	O
nested	O
arrays	O
,	O
and	O
shared	B-Language
variables	I-Language
.	O
</s>
<s>
APL	B-General_Concept
interpreters	B-Application
were	O
available	O
from	O
other	O
mainframe	O
and	O
mini-computer	O
manufacturers	O
also	O
,	O
notably	O
Burroughs	O
,	O
Control	O
Data	O
Corporation	O
(	O
CDC	O
)	O
,	O
Data	O
General	O
,	O
Digital	O
Equipment	O
Corporation	O
(	O
DEC	O
)	O
,	O
Harris	O
,	O
Hewlett-Packard	O
(	O
HP	O
)	O
,	O
Siemens	O
,	O
Xerox	O
and	O
others	O
.	O
</s>
<s>
Garth	O
Foster	O
of	O
Syracuse	O
University	O
sponsored	O
regular	O
meetings	O
of	O
the	O
APL	B-General_Concept
implementers	O
 '	O
community	O
at	O
Syracuse	O
's	O
Minnowbrook	O
Conference	O
Center	O
in	O
Blue	O
Mountain	O
Lake	O
,	O
New	O
York	O
.	O
</s>
<s>
The	O
SIGAPL	O
special	O
interest	O
group	O
of	O
the	O
Association	O
for	O
Computing	O
Machinery	O
continues	O
to	O
support	O
the	O
APL	B-General_Concept
community	O
.	O
</s>
<s>
On	O
microcomputers	B-Architecture
,	O
which	O
became	O
available	O
from	O
the	O
mid-1970s	O
onwards	O
,	O
BASIC	O
became	O
the	O
dominant	O
programming	O
language	O
.	O
</s>
<s>
Nevertheless	O
,	O
some	O
microcomputers	B-Architecture
provided	O
APL	B-General_Concept
instead	O
–	O
the	O
first	O
being	O
the	O
Intel	O
8008-based	O
MCM/70	B-Device
which	O
was	O
released	O
in	O
1974	O
and	O
which	O
was	O
primarily	O
used	O
in	O
education	O
.	O
</s>
<s>
Another	O
machine	O
of	O
this	O
time	O
was	O
the	O
VideoBrain	B-Device
Family	I-Device
Computer	I-Device
,	O
released	O
in	O
1977	O
,	O
which	O
was	O
supplied	O
with	O
its	O
dialect	O
of	O
APL	B-General_Concept
called	O
APL/S	O
.	O
</s>
<s>
The	O
Commodore	B-Device
SuperPET	I-Device
,	O
introduced	O
in	O
1981	O
,	O
included	O
an	O
APL	B-General_Concept
interpreter	B-Application
developed	O
by	O
the	O
University	O
of	O
Waterloo	O
.	O
</s>
<s>
In	O
1976	O
,	O
Bill	O
Gates	O
claimed	O
in	O
his	O
Open	O
Letter	O
to	O
Hobbyists	O
that	O
Microsoft	O
Corporation	O
was	O
implementing	O
APL	B-General_Concept
for	O
the	O
Intel	B-General_Concept
8080	I-General_Concept
and	O
Motorola	B-Device
6800	I-Device
but	O
had	O
"	O
very	O
little	O
incentive	O
to	O
make	O
 [ it ] 	O
available	O
to	O
hobbyists	O
"	O
because	O
of	O
software	O
piracy	O
.	O
</s>
<s>
Starting	O
in	O
the	O
early	O
1980s	O
,	O
IBM	O
APL	B-General_Concept
development	O
,	O
under	O
the	O
leadership	O
of	O
Jim	O
Brown	O
,	O
implemented	O
a	O
new	O
version	O
of	O
the	O
APL	B-General_Concept
language	O
that	O
contained	O
as	O
its	O
primary	O
enhancement	O
the	O
concept	O
of	O
nested	O
arrays	O
,	O
where	O
an	O
array	B-Application
can	O
contain	O
other	O
arrays	O
,	O
and	O
new	O
language	O
features	O
which	O
facilitated	O
integrating	O
nested	O
arrays	O
into	O
program	O
workflow	O
.	O
</s>
<s>
Ken	O
Iverson	O
,	O
no	O
longer	O
in	O
control	O
of	O
the	O
development	O
of	O
the	O
APL	B-General_Concept
language	O
,	O
left	O
IBM	O
and	O
joined	O
I	O
.	O
P	O
.	O
Sharp	O
Associates	O
,	O
where	O
one	O
of	O
his	O
major	O
contributions	O
was	O
directing	O
the	O
evolution	O
of	O
Sharp	O
APL	B-General_Concept
to	O
be	O
more	O
in	O
accord	O
with	O
his	O
vision	O
.	O
</s>
<s>
APL2	O
was	O
first	O
released	O
for	O
CMS	B-Operating_System
and	O
TSO	B-Application
in	O
1984	O
.	O
</s>
<s>
The	O
APL2	O
Workstation	O
edition	O
(	O
Windows	O
,	O
OS/2	B-Application
,	O
AIX	B-Application
,	O
Linux	B-Application
,	O
and	O
Solaris	B-Application
)	O
followed	O
later	O
.	O
</s>
<s>
As	O
other	O
vendors	O
were	O
busy	O
developing	O
APL	B-General_Concept
interpreters	B-Application
for	O
new	O
hardware	O
,	O
notably	O
Unix-based	O
microcomputers	B-Architecture
,	O
APL2	O
was	O
almost	O
always	O
the	O
standard	O
chosen	O
for	O
new	O
APL	B-General_Concept
interpreter	B-Application
developments	O
.	O
</s>
<s>
Even	O
today	O
,	O
most	O
APL	B-General_Concept
vendors	O
or	O
their	O
users	O
cite	O
APL2	O
compatibility	O
,	O
as	O
a	O
selling	O
point	O
for	O
those	O
products	O
.	O
</s>
<s>
Various	O
implementations	O
of	O
APL	B-General_Concept
by	O
APLX	B-Language
,	O
Dyalog	O
,	O
et	O
al.	O
,	O
include	O
extensions	O
for	O
object-oriented	B-Language
programming	I-Language
,	O
support	O
for	O
.NET	B-Application
Framework	I-Application
,	O
XML-array	O
conversion	O
primitives	O
,	O
graphing	O
,	O
operating	O
system	O
interfaces	O
,	O
and	O
lambda	B-Language
calculus	I-Language
expressions	O
.	O
</s>
<s>
Freeware	O
versions	O
include	O
GNU	O
APL	B-General_Concept
for	O
Linux	B-Application
and	O
NARS2000	O
for	O
Windows	O
(	O
which	O
runs	O
on	O
Linux	B-Application
under	O
Wine	B-Application
)	O
.	O
</s>
<s>
APL	B-General_Concept
has	O
formed	O
the	O
basis	O
of	O
,	O
or	O
influenced	O
,	O
the	O
following	O
languages	O
:	O
</s>
<s>
A	B-Language
and	I-Language
A+	I-Language
,	O
an	O
alternative	O
APL	B-General_Concept
,	O
the	O
latter	O
with	O
graphical	O
extensions	O
.	O
</s>
<s>
FP	B-Language
,	O
a	O
functional	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
Ivy	O
,	O
an	O
interpreter	B-Application
for	O
an	O
APL-like	O
language	O
developed	O
by	O
Rob	O
Pike	O
,	O
and	O
which	O
uses	O
ASCII	B-Protocol
as	O
input	O
.	O
</s>
<s>
J	B-Language
,	O
which	O
was	O
also	O
designed	O
by	O
Iverson	O
,	O
and	O
which	O
uses	O
ASCII	B-Protocol
with	O
digraphs	B-Language
instead	O
of	O
special	O
symbols	O
.	O
</s>
<s>
K	B-Application
,	O
a	O
proprietary	B-Application
variant	O
of	O
APL	B-General_Concept
developed	O
by	O
Arthur	O
Whitney	O
.	O
</s>
<s>
MATLAB	B-Language
,	O
a	O
numerical	O
computation	O
tool	O
.	O
</s>
<s>
Nial	B-Language
,	O
a	O
high-level	O
array	B-Application
programming	I-Application
language	I-Application
with	O
a	O
functional	B-Language
programming	I-Language
notation	O
.	O
</s>
<s>
Polymorphic	B-Language
Programming	I-Language
Language	I-Language
,	O
an	O
interactive	O
,	O
extensible	O
language	O
with	O
a	O
similar	O
base	O
language	O
.	O
</s>
<s>
S	B-Language
,	O
a	O
statistical	O
programming	O
language	O
(	O
usually	O
now	O
seen	O
in	O
the	O
open-source	B-Application
version	O
known	O
as	O
R	B-Language
)	O
.	O
</s>
<s>
Speakeasy	B-General_Concept
,	O
a	O
numerical	O
computing	O
interactive	O
environment	O
.	O
</s>
<s>
Wolfram	B-Language
Language	I-Language
,	O
the	O
programming	O
language	O
of	O
Mathematica	B-Language
.	O
</s>
<s>
APL	B-General_Concept
has	O
been	O
criticized	O
and	O
praised	O
for	O
its	O
choice	O
of	O
a	O
unique	O
,	O
non-standard	O
character	B-General_Concept
set	I-General_Concept
.	O
</s>
<s>
In	O
the	O
1960s	O
and	O
1970s	O
,	O
few	O
terminal	O
devices	O
or	O
even	O
displays	O
could	O
reproduce	O
the	O
APL	B-General_Concept
character	B-General_Concept
set	I-General_Concept
.	O
</s>
<s>
The	O
most	O
popular	O
ones	O
employed	O
the	O
IBM	O
Selectric	O
print	O
mechanism	O
used	O
with	O
a	O
special	O
APL	B-General_Concept
type	O
element	O
.	O
</s>
<s>
One	O
of	O
the	O
early	O
APL	B-General_Concept
line	B-General_Concept
terminals	I-General_Concept
(	O
line-mode	O
operation	O
only	O
,	O
not	O
full	O
screen	O
)	O
was	O
the	O
Texas	O
Instruments	O
TI	O
Model	O
745	O
(	O
)	O
with	O
the	O
full	O
APL	B-General_Concept
character	B-General_Concept
set	I-General_Concept
which	O
featured	O
half	O
and	O
full	O
duplex	O
telecommunications	O
modes	O
,	O
for	O
interacting	O
with	O
an	O
APL	B-General_Concept
time-sharing	B-General_Concept
service	O
or	O
remote	O
mainframe	O
to	O
run	O
a	O
remote	O
computer	O
job	O
,	O
called	B-Protocol
an	I-Protocol
RJE	I-Protocol
.	O
</s>
<s>
Over	O
time	O
,	O
with	O
the	O
universal	O
use	O
of	O
high-quality	O
graphic	O
displays	O
,	O
printing	O
devices	O
and	O
Unicode	O
support	O
,	O
the	O
APL	B-General_Concept
character	O
font	O
problem	O
has	O
largely	O
been	O
eliminated	O
.	O
</s>
<s>
However	O
,	O
entering	O
APL	B-General_Concept
characters	O
requires	O
the	O
use	O
of	O
input	B-General_Concept
method	I-General_Concept
editors	I-General_Concept
,	O
keyboard	B-Device
mappings	O
,	O
virtual/on	O
-screen	O
APL	B-Language
symbol	I-Language
sets	O
,	O
or	O
easy-reference	O
printed	O
keyboard	B-Device
cards	O
which	O
can	O
frustrate	O
beginners	O
accustomed	O
to	O
other	O
programming	O
languages	O
.	O
</s>
<s>
With	O
beginners	O
who	O
have	O
no	O
prior	O
experience	O
with	O
other	O
programming	O
languages	O
,	O
a	O
study	O
involving	O
high	O
school	O
students	O
found	O
that	O
typing	O
and	O
using	O
APL	B-General_Concept
characters	O
did	O
not	O
hinder	O
the	O
students	O
in	O
any	O
measurable	O
way	O
.	O
</s>
<s>
In	O
defense	O
of	O
APL	B-General_Concept
,	O
it	O
requires	O
fewer	O
characters	O
to	O
type	O
,	O
and	O
keyboard	B-Device
mappings	O
become	O
memorized	O
over	O
time	O
.	O
</s>
<s>
Special	O
APL	B-General_Concept
keyboards	B-Device
are	O
also	O
made	O
and	O
in	O
use	O
today	O
,	O
as	O
are	O
freely	O
downloadable	O
fonts	O
for	O
operating	O
systems	O
such	O
as	O
Microsoft	B-Application
Windows	I-Application
.	O
</s>
<s>
The	O
reported	O
productivity	O
gains	O
assume	O
that	O
one	O
spends	O
enough	O
time	O
working	O
in	O
the	O
language	O
to	O
make	O
it	O
worthwhile	O
to	O
memorize	O
the	O
symbols	O
,	O
their	O
semantics	O
,	O
and	O
keyboard	B-Device
mappings	O
,	O
not	O
to	O
mention	O
a	O
substantial	O
number	O
of	O
idioms	O
for	O
common	O
tasks	O
.	O
</s>
<s>
Unlike	O
traditionally	O
structured	B-Language
programming	I-Language
languages	O
,	O
APL	B-General_Concept
code	O
is	O
typically	O
structured	B-Language
as	O
chains	O
of	O
monadic	O
or	O
dyadic	O
functions	O
,	O
and	O
operators	B-Language
acting	O
on	O
arrays	O
.	O
</s>
<s>
APL	B-General_Concept
has	O
many	O
nonstandard	O
primitives	O
(	O
functions	O
and	O
operators	B-Language
)	O
that	O
are	O
indicated	O
by	O
a	O
single	O
symbol	O
or	O
a	O
combination	O
of	O
a	O
few	O
symbols	O
.	O
</s>
<s>
Thus	O
,	O
APL	B-General_Concept
is	O
read	O
or	O
best	O
understood	O
from	O
right-to-left	O
.	O
</s>
<s>
Early	O
APL	B-General_Concept
implementations	O
(	O
or	O
so	O
)	O
had	O
no	O
programming	O
loop-flow	O
control	O
structures	O
,	O
such	O
as	O
do	O
or	O
while	O
loops	O
,	O
and	O
if-then-else	O
constructs	O
.	O
</s>
<s>
Instead	O
,	O
they	O
used	O
array	B-Application
operations	O
,	O
and	O
use	O
of	O
structured	B-Language
programming	I-Language
constructs	O
was	O
often	O
not	O
necessary	O
,	O
since	O
an	O
operation	O
could	O
be	O
performed	O
on	O
a	O
full	O
array	B-Application
in	O
one	O
statement	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
iota	B-Protocol
function	O
( ι	O
)	O
can	O
replace	O
for-loop	O
iteration	B-Algorithm
:	O
ιN	O
when	O
applied	O
to	O
a	O
scalar	O
positive	O
integer	O
yields	O
a	O
one-dimensional	O
array	B-Application
(	O
vector	B-Data_Structure
)	O
,	O
1	O
2	O
3	O
...	O
N	O
.	O
More	O
recent	O
implementations	O
of	O
APL	B-General_Concept
generally	O
include	O
comprehensive	O
control	O
structures	O
,	O
so	O
that	O
data	O
structure	O
and	O
program	O
control	O
flow	O
can	O
be	O
clearly	O
and	O
cleanly	O
separated	O
.	O
</s>
<s>
The	O
APL	B-General_Concept
environment	O
is	O
called	O
a	O
workspace	O
.	O
</s>
<s>
In	O
the	O
examples	O
below	O
,	O
the	O
APL	B-General_Concept
interpreter	B-Application
first	O
types	O
six	O
spaces	O
before	O
awaiting	O
the	O
user	O
's	O
input	O
.	O
</s>
<s>
n	O
←	O
4	O
5	O
6	O
7	O
Assigns	O
vector	B-Data_Structure
of	O
values	O
,	O
{	O
4	O
5	O
6	O
7}	O
,	O
to	O
variable	O
n	O
,	O
an	O
array	B-Application
create	O
operation	O
.	O
</s>
<s>
An	O
equivalent	O
yet	O
more	O
concise	O
APL	B-General_Concept
expression	O
would	O
be	O
n	O
←	O
3	O
+	O
⍳4	O
.	O
</s>
<s>
Multiple	O
values	O
are	O
stored	O
in	O
array	B-Application
n	O
,	O
the	O
operation	O
performed	O
without	O
formal	O
loops	O
or	O
control	O
flow	O
language	O
.	O
</s>
<s>
4	O
5	O
6	O
7	O
Display	O
the	O
contents	O
of	O
n	O
,	O
currently	O
an	O
array	B-Application
or	O
vector	B-Data_Structure
.	O
</s>
<s>
8	O
9	O
10	O
11	O
4	O
is	O
now	O
added	O
to	O
all	O
elements	O
of	O
vector	B-Data_Structure
n	O
,	O
creating	O
a	O
4-element	O
vector	B-Data_Structure
{	O
8	O
9	O
10	O
11}	O
.	O
</s>
<s>
As	O
above	O
,	O
APL	B-General_Concept
's	O
interpreter	B-Application
displays	O
the	O
result	O
because	O
the	O
expression	O
's	O
value	O
was	O
not	O
assigned	O
to	O
a	O
variable	O
(	O
with	O
a	O
←	O
)	O
.	O
</s>
<s>
22	O
These	O
operations	O
can	O
be	O
combined	O
into	O
one	O
statement	O
,	O
remembering	O
that	O
APL	B-General_Concept
evaluates	O
expressions	O
right	O
to	O
left	O
:	O
first	O
⍳4	O
creates	O
an	O
array	B-Application
,	O
[1,2,3,4],	O
then	O
3	O
is	O
added	O
to	O
each	O
component	O
,	O
which	O
are	O
summed	O
together	O
and	O
the	O
result	O
stored	O
in	O
variable	O
m	O
,	O
finally	O
displayed	O
.	O
</s>
<s>
APL	B-General_Concept
uses	O
a	O
set	O
of	O
non-ASCII	O
symbols	O
,	O
which	O
are	O
an	O
extension	O
of	O
traditional	O
arithmetic	O
and	O
algebraic	O
notation	O
.	O
</s>
<s>
Having	O
single	O
character	O
names	O
for	O
single	B-Device
instruction	I-Device
,	I-Device
multiple	I-Device
data	I-Device
(	O
SIMD	B-Device
)	O
vector	B-Data_Structure
functions	O
is	O
one	O
way	O
that	O
APL	B-General_Concept
enables	O
compact	O
formulation	O
of	O
algorithms	O
for	O
data	O
transformation	O
such	O
as	O
computing	O
Conway	O
's	O
Game	O
of	O
Life	O
in	O
one	O
line	O
of	O
code	O
.	O
</s>
<s>
In	O
nearly	O
all	O
versions	O
of	O
APL	B-General_Concept
,	O
it	O
is	O
theoretically	O
possible	O
to	O
express	O
any	O
computable	O
function	O
in	O
one	O
expression	O
,	O
that	O
is	O
,	O
in	O
one	O
line	O
of	O
code	O
.	O
</s>
<s>
Because	O
of	O
the	O
unusual	O
character	B-General_Concept
set	I-General_Concept
,	O
many	O
programmers	B-Application
use	O
special	O
keyboards	B-Device
with	O
APL	B-General_Concept
keytops	O
to	O
write	O
APL	B-General_Concept
code	O
.	O
</s>
<s>
Although	O
there	O
are	O
various	O
ways	O
to	O
write	O
APL	B-General_Concept
code	O
using	O
only	O
ASCII	B-Protocol
characters	I-Protocol
,	O
in	O
practice	O
it	O
is	O
almost	O
never	O
done	O
.	O
</s>
<s>
(	O
This	O
may	O
be	O
thought	O
to	O
support	O
Iverson	O
's	O
thesis	O
about	O
notation	O
as	O
a	O
tool	O
of	O
thought	O
.	O
)	O
</s>
<s>
Most	O
if	O
not	O
all	O
modern	O
implementations	O
use	O
standard	O
keyboard	B-Device
layouts	O
,	O
with	O
special	O
mappings	O
or	O
input	B-General_Concept
method	I-General_Concept
editors	I-General_Concept
to	O
access	O
non-ASCII	O
characters	O
.	O
</s>
<s>
Historically	O
,	O
the	O
APL	B-General_Concept
font	O
has	O
been	O
distinctive	O
,	O
with	O
uppercase	O
italic	O
alphabetic	O
characters	O
and	O
upright	O
numerals	O
and	O
symbols	O
.	O
</s>
<s>
Most	O
vendors	O
continue	O
to	O
display	O
the	O
APL	B-General_Concept
character	B-General_Concept
set	I-General_Concept
in	O
a	O
custom	O
font	O
.	O
</s>
<s>
Advocates	O
of	O
APL	B-General_Concept
claim	O
that	O
the	O
examples	O
of	O
so-called	O
write-only	O
code	O
(	O
badly	O
written	O
and	O
almost	O
incomprehensible	O
code	O
)	O
are	O
almost	O
invariably	O
examples	O
of	O
poor	O
programming	O
practice	O
or	O
novice	O
mistakes	O
,	O
which	O
can	O
occur	O
in	O
any	O
language	O
.	O
</s>
<s>
Advocates	O
also	O
claim	O
that	O
they	O
are	O
far	O
more	O
productive	O
with	O
APL	B-General_Concept
than	O
with	O
more	O
conventional	O
computer	O
languages	O
,	O
and	O
that	O
working	O
software	O
can	O
be	O
implemented	O
in	O
far	O
less	O
time	O
and	O
with	O
far	O
fewer	O
programmers	B-Application
than	O
using	O
other	O
technology	O
.	O
</s>
<s>
They	O
also	O
may	O
claim	O
that	O
because	O
it	O
is	O
compact	O
and	O
terse	O
,	O
APL	B-General_Concept
lends	O
itself	O
well	O
to	O
larger-scale	O
software	O
development	O
and	O
complexity	O
,	O
because	O
the	O
number	O
of	O
lines	O
of	O
code	O
can	O
be	O
reduced	O
greatly	O
.	O
</s>
<s>
Many	O
APL	B-General_Concept
advocates	O
and	O
practitioners	O
also	O
view	O
standard	O
programming	O
languages	O
such	O
as	O
COBOL	B-Application
and	O
Java	B-Language
as	O
being	O
comparatively	O
tedious	O
.	O
</s>
<s>
APL	B-General_Concept
is	O
often	O
found	O
where	O
time-to-market	O
is	O
important	O
,	O
such	O
as	O
with	O
trading	O
systems	O
.	O
</s>
<s>
APL	B-General_Concept
makes	O
a	O
clear	O
distinction	O
between	O
functions	O
and	O
operators	B-Language
.	O
</s>
<s>
Operators	B-Language
(	O
similar	O
to	O
higher-order	B-Language
functions	I-Language
)	O
take	O
functions	O
or	O
arrays	O
as	O
arguments	O
,	O
and	O
derive	O
related	O
functions	O
.	O
</s>
<s>
Applying	O
the	O
same	O
reduction	O
operator	O
to	O
the	O
maximum	O
function	O
(	O
which	O
returns	O
the	O
larger	O
of	O
two	O
numbers	O
)	O
derives	O
a	O
function	O
which	O
returns	O
the	O
largest	O
of	O
a	O
group	O
(	O
vector	B-Data_Structure
)	O
of	O
numbers	O
.	O
</s>
<s>
In	O
the	O
J	B-Language
language	O
,	O
Iverson	O
substituted	O
the	O
terms	O
verb	O
for	O
function	O
and	O
adverb	O
or	O
conjunction	O
for	O
operator	O
.	O
</s>
<s>
APL	B-General_Concept
also	O
identifies	O
those	O
features	O
built	O
into	O
the	O
language	O
,	O
and	O
represented	O
by	O
a	O
symbol	O
,	O
or	O
a	O
fixed	O
combination	O
of	O
symbols	O
,	O
as	O
primitives	O
.	O
</s>
<s>
Most	O
primitives	O
are	O
either	O
functions	O
or	O
operators	B-Language
.	O
</s>
<s>
Coding	O
APL	B-General_Concept
is	O
largely	O
a	O
process	O
of	O
writing	O
non-primitive	O
functions	O
and	O
(	O
in	O
some	O
versions	O
of	O
APL	B-General_Concept
)	O
operators	B-Language
.	O
</s>
<s>
However	O
a	O
few	O
primitives	O
are	O
considered	O
to	O
be	O
neither	O
functions	O
nor	O
operators	B-Language
,	O
most	O
noticeably	O
assignment	O
.	O
</s>
<s>
Some	O
words	O
used	O
in	O
APL	B-General_Concept
literature	O
have	O
meanings	O
that	O
differ	O
from	O
those	O
in	O
both	O
mathematics	O
and	O
the	O
generality	O
of	O
computer	O
science	O
.	O
</s>
<s>
+Terminology	O
of	O
APL	B-Language
operators	I-Language
Term	O
Description	O
function	O
operation	O
or	O
mapping	O
that	O
takes	O
zero	O
,	O
one	O
(	O
right	O
)	O
or	O
two	O
(	O
left	O
&	O
right	O
)	O
arguments	O
which	O
may	O
be	O
scalars	O
,	O
arrays	O
,	O
or	O
more	O
complicated	O
structures	O
,	O
and	O
may	O
return	O
a	O
similarly	O
complex	O
result	O
.	O
</s>
<s>
array	B-Application
data	O
valued	O
object	O
of	O
zero	O
or	O
more	O
orthogonal	O
dimensions	O
in	O
row-major	B-Data_Structure
order	I-Data_Structure
in	O
which	O
each	O
item	O
is	O
a	O
primitive	O
scalar	O
datum	O
or	O
another	O
array	B-Application
.	O
</s>
<s>
niladic	O
not	O
taking	O
or	O
requiring	O
any	O
arguments	O
,	O
nullary	O
"	O
Programmera	O
i	O
APL	B-General_Concept
"	O
,	O
Bohman	O
,	O
Fröberg	O
,	O
Studentlitteratur	O
,	O
monadic	O
requiring	O
only	O
one	O
argument	O
;	O
on	O
the	O
right	O
for	O
a	O
function	O
,	O
on	O
the	O
left	O
for	O
an	O
operator	O
,	O
unary	O
dyadic	O
requiring	O
both	O
a	O
left	O
and	O
a	O
right	O
argument	O
,	O
binary	O
ambivalent	O
or	O
monadic	O
capable	O
of	O
use	O
in	O
a	O
monadic	O
or	O
dyadic	O
context	O
,	O
permitting	O
its	O
left	O
argument	O
to	O
be	O
elided	O
operator	O
operation	O
or	O
mapping	O
that	O
takes	O
one	O
(	O
left	O
)	O
or	O
two	O
(	O
left	O
&	O
right	O
)	O
function	O
or	O
array	B-Application
valued	O
arguments	O
(	O
operands	O
)	O
and	O
derives	O
a	O
function	O
.	O
</s>
<s>
APL	B-General_Concept
has	O
explicit	O
representations	O
of	O
functions	O
,	O
operators	B-Language
,	O
and	O
syntax	O
,	O
thus	O
providing	O
a	O
basis	O
for	O
the	O
clear	O
and	O
explicit	O
statement	O
of	O
extended	O
facilities	O
in	O
the	O
language	O
,	O
and	O
tools	O
to	O
experiment	O
on	O
them	O
.	O
</s>
<s>
A	O
design	O
theme	O
in	O
APL	B-General_Concept
is	O
to	O
define	O
default	O
actions	O
in	O
some	O
cases	O
that	O
would	O
produce	O
syntax	O
errors	O
in	O
most	O
other	O
programming	O
languages	O
.	O
</s>
<s>
Another	O
example	O
of	O
this	O
theme	O
is	O
that	O
exponentiation	O
in	O
APL	B-General_Concept
is	O
written	O
as	O
,	O
which	O
indicates	O
raising	O
2	O
to	O
the	O
power	O
3	O
(	O
this	O
would	O
be	O
written	O
as	O
in	O
some	O
other	O
languages	O
and	O
in	O
FORTRAN	B-Application
and	O
Python	B-Language
)	O
.	O
</s>
<s>
Many	O
languages	O
use	O
to	O
signify	O
multiplication	O
,	O
as	O
in	O
,	O
but	O
APL	B-General_Concept
chooses	O
to	O
use	O
.	O
</s>
<s>
However	O
,	O
if	O
no	O
base	O
is	O
specified	O
(	O
as	O
with	O
the	O
statement	O
in	O
APL	B-General_Concept
,	O
or	O
in	O
other	O
languages	O
)	O
,	O
most	O
programming	O
languages	O
one	O
would	O
see	O
this	O
as	O
a	O
syntax	O
error	O
.	O
</s>
<s>
APL	B-General_Concept
,	O
however	O
,	O
assumes	O
the	O
missing	O
base	O
to	O
be	O
the	O
natural	O
logarithm	O
constant	O
e	O
,	O
and	O
interprets	O
as	O
.	O
</s>
<s>
Suppose	O
that	O
is	O
an	O
array	B-Application
of	O
numbers	O
.	O
</s>
<s>
Building	O
on	O
this	O
,	O
the	O
following	O
expression	O
computes	O
standard	B-General_Concept
deviation	I-General_Concept
:	O
</s>
<s>
This	O
following	O
immediate-mode	O
expression	O
generates	O
a	O
typical	O
set	O
of	O
Pick	O
6	O
lottery	O
numbers	O
:	O
six	O
pseudo-random	B-Error_Name
integers	O
ranging	O
from	O
1	O
to	O
40	O
,	O
guaranteed	O
non-repeating	O
,	O
and	O
displays	O
them	O
sorted	O
in	O
ascending	O
order	O
:	O
</s>
<s>
It	O
combines	O
the	O
following	O
APL	B-General_Concept
functions	O
(	O
also	O
called	O
primitives	O
and	O
glyphs	O
)	O
:	O
</s>
<s>
The	O
first	O
to	O
be	O
executed	O
(	O
APL	B-General_Concept
executes	O
from	O
rightmost	O
to	O
leftmost	O
)	O
is	O
dyadic	O
function	O
?	O
</s>
<s>
(	O
named	O
deal	O
when	O
dyadic	O
)	O
that	O
returns	O
a	O
vector	B-Data_Structure
consisting	O
of	O
a	O
select	O
number	O
(	O
left	O
argument	O
:	O
6	O
in	O
this	O
case	O
)	O
of	O
random	O
integers	O
ranging	O
from	O
1	O
to	O
a	O
specified	O
maximum	O
(	O
right	O
argument	O
:	O
40	O
in	O
this	O
case	O
)	O
,	O
which	O
,	O
if	O
said	O
maximum	O
≥	O
vector	B-Data_Structure
length	O
,	O
is	O
guaranteed	O
to	O
be	O
non-repeating	O
;	O
thus	O
,	O
generate/create	O
6	O
random	O
integers	O
ranging	O
from	O
1	O
to	O
40	O
.	O
</s>
<s>
This	O
vector	B-Data_Structure
is	O
then	O
assigned	O
(	O
←	O
)	O
to	O
the	O
variable	O
x	O
,	O
because	O
it	O
is	O
needed	O
later	O
.	O
</s>
<s>
This	O
vector	B-Data_Structure
is	O
then	O
sorted	O
in	O
ascending	O
order	O
by	O
a	O
monadic	O
⍋	B-Language
function	O
,	O
which	O
has	O
as	O
its	O
right	O
argument	O
everything	O
to	O
the	O
right	O
of	O
it	O
up	O
to	O
the	O
next	O
unbalanced	O
close-bracket	O
or	O
close-parenthesis	O
.	O
</s>
<s>
The	O
result	O
of	O
⍋	B-Language
is	O
the	O
indices	O
that	O
will	O
put	O
its	O
argument	O
into	O
ascending	O
order	O
.	O
</s>
<s>
Then	O
the	O
output	O
of	O
⍋	B-Language
is	O
used	O
to	O
index	O
the	O
variable	O
x	O
,	O
which	O
we	O
saved	O
earlier	O
for	O
this	O
purpose	O
,	O
thereby	O
selecting	O
its	O
items	O
in	O
ascending	O
sequence	O
.	O
</s>
<s>
Since	O
there	O
is	O
no	O
function	O
to	O
the	O
left	O
of	O
the	O
left-most	O
x	O
to	O
tell	O
APL	B-General_Concept
what	O
to	O
do	O
with	O
the	O
result	O
,	O
it	O
simply	O
outputs	O
it	O
to	O
the	O
display	O
(	O
on	O
a	O
single	O
line	O
,	O
separated	O
by	O
spaces	O
)	O
without	O
needing	O
any	O
explicit	O
instruction	O
to	O
do	O
that	O
.	O
</s>
<s>
The	O
following	O
expression	O
finds	O
all	O
prime	O
numbers	O
from	O
1	O
to	O
R	B-Language
.	O
In	O
both	O
time	O
and	O
space	O
,	O
the	O
calculation	O
complexity	O
is	O
(	O
in	O
Big	O
O	O
notation	O
)	O
.	O
</s>
<s>
Drop	O
first	O
element	O
of	O
this	O
vector	B-Data_Structure
(	O
↓	O
function	O
)	O
,	O
i.e.	O
,	O
1	O
.	O
</s>
<s>
The	O
/	O
replicate	O
operator	O
is	O
dyadic	O
(	O
binary	O
)	O
and	O
the	O
interpreter	B-Application
first	O
evaluates	O
its	O
left	O
argument	O
(	O
fully	O
in	O
parentheses	O
)	O
:	O
</s>
<s>
Generate	O
outer	O
product	O
of	O
R	B-Language
multiplied	O
by	O
R	B-Language
,	O
i.e.	O
,	O
a	O
matrix	O
that	O
is	O
the	O
multiplication	O
table	O
of	O
R	B-Language
by	O
R	B-Language
( °	O
.	O
×	O
operator	O
)	O
,	O
i.e.	O
,	O
</s>
<s>
(	O
Note	O
,	O
this	O
assumes	O
the	O
APL	B-General_Concept
origin	O
is	O
1	O
,	O
i.e.	O
,	O
indices	O
start	O
with	O
1	O
.	O
</s>
<s>
APL	B-General_Concept
can	O
be	O
set	O
to	O
use	O
0	O
as	O
the	O
origin	O
,	O
so	O
that	O
ι6	O
is	O
0	O
1	O
2	O
3	O
4	O
5	O
,	O
which	O
is	O
convenient	O
for	O
some	O
calculations	O
.	O
)	O
</s>
<s>
The	O
following	O
expression	O
sorts	B-Algorithm
a	O
word	O
list	O
stored	O
in	O
matrix	O
X	O
according	O
to	O
word	O
length	O
:	O
</s>
<s>
The	O
following	O
function	O
"	O
life	O
"	O
,	O
written	O
in	O
Dyalog	O
APL	B-General_Concept
,	O
takes	O
a	O
boolean	O
matrix	O
and	O
calculates	O
the	O
new	O
generation	O
according	O
to	O
Conway	O
's	O
Game	O
of	O
Life	O
.	O
</s>
<s>
It	O
demonstrates	O
the	O
power	O
of	O
APL	B-General_Concept
to	O
implement	O
a	O
complex	O
algorithm	O
in	O
very	O
little	O
code	O
,	O
but	O
understanding	O
it	O
requires	O
some	O
advanced	O
knowledge	O
of	O
APL	B-General_Concept
(	O
as	O
the	O
same	O
program	O
would	O
in	O
many	O
languages	O
)	O
.	O
</s>
<s>
In	O
the	O
following	O
example	O
,	O
also	O
Dyalog	O
,	O
the	O
first	O
line	O
assigns	O
some	O
HTML	O
code	O
to	O
a	O
variable	O
txt	O
and	O
then	O
uses	O
an	O
APL	B-General_Concept
expression	O
to	O
remove	O
all	O
the	O
HTML	O
tags	O
(	O
)	O
:	O
</s>
<s>
APL	B-General_Concept
derives	O
its	O
name	O
from	O
the	O
initials	O
of	O
Iverson	O
's	O
book	O
A	O
Programming	O
Language	O
,	O
even	O
though	O
the	O
book	O
describes	O
Iverson	O
's	O
mathematical	O
notation	O
,	O
rather	O
than	O
the	O
implemented	O
programming	O
language	O
described	O
in	O
this	O
article	O
.	O
</s>
<s>
The	O
name	O
is	O
used	O
only	O
for	O
actual	O
implementations	O
,	O
starting	O
with	O
APL	B-General_Concept
\360	O
.	O
</s>
<s>
Adin	O
Falkoff	O
coined	O
the	O
name	O
in	O
1966	O
during	O
the	O
implementation	O
of	O
APL	B-General_Concept
\360	O
at	O
IBM	O
:	O
</s>
<s>
APL	B-General_Concept
is	O
occasionally	O
re-interpreted	O
as	O
Array	B-Application
Programming	I-Application
Language	I-Application
or	O
Array	B-Application
Processing	O
Language	O
,	O
thereby	O
making	O
APL	B-General_Concept
into	O
a	O
backronym	O
.	O
</s>
<s>
There	O
has	O
always	O
been	O
cooperation	O
between	O
APL	B-General_Concept
vendors	O
,	O
and	O
joint	O
conferences	O
were	O
held	O
on	O
a	O
regular	O
basis	O
from	O
1969	O
until	O
2010	O
.	O
</s>
<s>
At	O
such	O
conferences	O
,	O
APL	B-General_Concept
merchandise	B-Device
was	O
often	O
handed	O
out	O
,	O
featuring	O
APL	B-General_Concept
motifs	O
or	O
collection	O
of	O
vendor	O
logos	O
.	O
</s>
<s>
Common	O
were	O
apples	O
(	O
as	O
a	O
pun	O
on	O
the	O
similarity	O
in	O
pronunciation	O
of	O
apple	O
and	O
APL	B-General_Concept
)	O
and	O
the	O
code	O
snippet	O
which	O
are	O
the	O
symbols	O
produced	O
by	O
the	O
classic	O
APL	B-General_Concept
keyboard	B-Device
layout	O
when	O
holding	O
the	O
APL	B-General_Concept
modifier	B-Device
key	I-Device
and	O
typing	O
"	O
APL	B-General_Concept
"	O
.	O
</s>
<s>
As	O
popular	O
programming	O
languages	O
increasingly	O
have	O
established	O
recognisable	O
logos	O
,	O
Fortran	B-Application
getting	O
one	O
in	O
2020	O
,	O
British	O
APL	B-General_Concept
Association	O
launched	O
a	O
campaign	O
in	O
the	O
second	O
half	O
of	O
2021	O
,	O
to	O
establish	O
such	O
a	O
logo	O
for	O
APL	B-General_Concept
,	O
and	O
after	O
a	O
community	O
election	O
and	O
multiple	O
rounds	O
of	O
feedback	O
,	O
a	O
logo	O
was	O
chosen	O
in	O
May	O
2022	O
.	O
</s>
<s>
APL	B-General_Concept
is	O
used	O
for	O
many	O
purposes	O
including	O
financial	B-Application
and	O
insurance	O
applications	O
,	O
artificial	B-Application
intelligence	I-Application
,	O
</s>
<s>
It	O
has	O
been	O
argued	O
that	O
APL	B-General_Concept
is	O
a	O
calculation	O
tool	O
and	O
not	O
a	O
programming	O
language	O
;	O
its	O
symbolic	O
nature	O
and	O
array	B-Application
capabilities	O
have	O
made	O
it	O
popular	O
with	O
domain	O
experts	O
and	O
data	O
scientists	O
who	O
do	O
not	O
have	O
or	O
require	O
the	O
skills	O
of	O
a	O
computer	B-Application
programmer	I-Application
.	O
</s>
<s>
APL	B-General_Concept
is	O
well	O
suited	O
to	O
image	B-Application
manipulation	I-Application
and	O
computer	O
animation	O
,	O
where	O
graphic	O
transformations	O
can	O
be	O
encoded	O
as	O
matrix	O
multiplications	O
.	O
</s>
<s>
One	O
of	O
the	O
first	O
commercial	O
computer	O
graphics	O
houses	O
,	O
Digital	O
Effects	O
,	O
produced	O
an	O
APL	B-General_Concept
graphics	O
product	O
named	O
Visions	O
,	O
which	O
was	O
used	O
to	O
create	O
television	O
commercials	O
and	O
animation	O
for	O
the	O
1982	O
film	O
Tron	B-Language
.	O
</s>
<s>
Latterly	O
,	O
the	O
boating	O
simulator	O
uses	O
APL	B-General_Concept
to	O
implement	O
its	O
core	O
logic	O
,	O
its	O
interfacing	O
to	O
the	O
rendering	O
pipeline	O
middleware	O
and	O
a	O
major	O
part	O
of	O
its	O
physics	O
engine	O
.	O
</s>
<s>
The	O
first	O
implementation	O
of	O
APL	B-General_Concept
using	O
recognizable	O
APL	B-Language
symbols	I-Language
was	O
APL	B-General_Concept
\360	O
which	O
ran	O
on	O
the	O
IBM	B-Application
System/360	I-Application
,	O
and	O
was	O
completed	O
in	O
November	O
1966	O
though	O
at	O
that	O
time	O
remained	O
in	O
use	O
only	O
within	O
IBM	O
.	O
</s>
<s>
It	O
was	O
given	O
"	O
for	O
their	O
work	O
in	O
the	O
design	O
and	O
implementation	O
of	O
APL	B-General_Concept
\360,	O
setting	O
new	O
standards	O
in	O
simplicity	O
,	O
efficiency	O
,	O
reliability	O
and	O
response	O
time	O
for	O
interactive	O
systems.	O
"	O
</s>
<s>
In	O
1975	O
,	O
the	O
IBM	B-Device
5100	I-Device
microcomputer	B-Architecture
offered	O
APL	B-General_Concept
\360	O
as	O
one	O
of	O
two	O
built-in	O
ROM-based	O
interpreted	B-Application
languages	I-Application
for	O
the	O
computer	O
,	O
complete	O
with	O
a	O
keyboard	B-Device
and	O
display	O
that	O
supported	O
all	O
the	O
special	O
symbols	O
used	O
in	O
the	O
language	O
.	O
</s>
<s>
Significant	O
developments	O
to	O
APL	B-General_Concept
\360	O
included	O
CMS/APL	O
,	O
which	O
made	O
use	O
of	O
the	O
virtual	B-Architecture
storage	I-Architecture
capabilities	O
of	O
CMS	B-Operating_System
and	O
APLSV	O
,	O
which	O
introduced	O
shared	B-Language
variables	I-Language
,	O
system	O
variables	O
and	O
system	O
functions	O
.	O
</s>
<s>
It	O
was	O
subsequently	O
ported	O
to	O
the	O
IBM	B-Device
System/370	I-Device
and	O
VSPC	O
platforms	O
until	O
its	O
final	O
release	O
in	O
1983	O
,	O
after	O
which	O
it	O
was	O
replaced	O
by	O
APL2	O
.	O
</s>
<s>
In	O
1968	O
,	O
APL	B-General_Concept
\1130	O
became	O
the	O
first	O
publicly	O
available	O
APL	B-General_Concept
system	O
,	O
created	O
by	O
IBM	O
for	O
the	O
IBM	B-Device
1130	I-Device
.	O
</s>
<s>
It	O
became	O
the	O
most	O
popular	O
IBM	B-Application
Type-III	I-Application
Library	I-Application
software	O
that	O
IBM	O
released	O
.	O
</s>
<s>
APL*Plus	O
and	O
Sharp	O
APL	B-General_Concept
are	O
versions	O
of	O
APL	B-General_Concept
\360	O
with	O
added	O
business-oriented	O
extensions	O
such	O
as	O
data	O
formatting	O
and	O
facilities	O
to	O
store	O
APL	B-General_Concept
arrays	O
in	O
external	O
files	O
.	O
</s>
<s>
They	O
were	O
jointly	O
developed	O
by	O
two	O
companies	O
,	O
employing	O
various	O
members	O
of	O
the	O
original	O
IBM	O
APL	B-General_Concept
\360	O
development	O
team	O
.	O
</s>
<s>
The	O
two	O
companies	O
were	O
I	O
.	O
P	O
.	O
Sharp	O
Associates	O
(	O
IPSA	O
)	O
,	O
an	O
APL	B-General_Concept
\360	O
services	O
company	O
formed	O
in	O
1964	O
by	O
Ian	O
Sharp	O
,	O
Roger	O
Moore	O
and	O
others	O
,	O
and	O
STSC	O
,	O
a	O
time-sharing	B-General_Concept
and	O
consulting	O
service	O
company	O
formed	O
in	O
1969	O
by	O
Lawrence	O
Breed	O
and	O
others	O
.	O
</s>
<s>
Together	O
the	O
two	O
developed	O
APL*Plus	O
and	O
thereafter	O
continued	O
to	O
work	O
together	O
but	O
develop	O
APL	B-General_Concept
separately	O
as	O
APL*Plus	O
and	O
Sharp	O
APL	B-General_Concept
.	O
</s>
<s>
STSC	O
ported	O
APL*Plus	O
to	O
many	O
platforms	O
with	O
versions	O
being	O
made	O
for	O
the	O
VAX	O
11	O
,	O
PC	O
and	O
UNIX	B-Application
,	O
whereas	O
IPSA	O
took	O
a	O
different	O
approach	O
to	O
the	O
arrival	O
of	O
the	O
personal	B-Device
computer	I-Device
and	O
made	O
Sharp	O
APL	B-General_Concept
available	O
on	O
this	O
platform	O
using	O
additional	O
PC-XT/360	B-Operating_System
hardware	O
.	O
</s>
<s>
In	O
1993	O
,	O
Soliton	O
Incorporated	O
was	O
formed	O
to	O
support	O
Sharp	O
APL	B-General_Concept
and	O
it	O
developed	O
Sharp	O
APL	B-General_Concept
into	O
SAX	O
(	O
Sharp	O
APL	B-General_Concept
for	O
Unix	B-Application
)	O
.	O
</s>
<s>
,	O
APL*Plus	O
continues	O
as	O
APL2000	O
APL+Win	O
.	O
</s>
<s>
In	O
1985	O
,	O
Ian	O
Sharp	O
,	O
and	O
Dan	O
Dyer	O
of	O
STSC	O
,	O
jointly	O
received	O
the	O
Kenneth	B-Language
E	I-Language
.	I-Language
Iverson	I-Language
Award	I-Language
for	I-Language
Outstanding	I-Language
Contribution	I-Language
to	I-Language
APL	I-Language
.	O
</s>
<s>
APL2	O
was	O
a	O
significant	O
re-implementation	O
of	O
APL	B-General_Concept
by	O
IBM	O
which	O
was	O
developed	O
from	O
1971	O
and	O
first	O
released	O
in	O
1984	O
.	O
</s>
<s>
It	O
provides	O
many	O
additions	O
to	O
the	O
language	O
,	O
of	O
which	O
the	O
most	O
notable	O
is	O
nested	O
(	O
non-rectangular	O
)	O
array	B-Application
support	O
.	O
</s>
<s>
The	O
entire	O
APL2	O
Products	O
and	O
Services	O
Team	O
was	O
awarded	O
the	O
Iverson	B-Language
Award	I-Language
in	O
2007	O
.	O
</s>
<s>
In	O
1972	O
,	O
APLGOL	O
was	O
released	O
as	O
an	O
experimental	O
version	O
of	O
APL	B-General_Concept
that	O
added	O
structured	B-Language
programming	I-Language
language	O
constructs	O
to	O
the	O
language	O
framework	O
.	O
</s>
<s>
Dyalog	O
APL	B-General_Concept
was	O
first	O
released	O
by	O
British	O
company	O
Dyalog	O
Ltd	O
.	O
in	O
1983	O
and	O
,	O
,	O
is	O
available	O
for	O
AIX	B-Application
,	O
Linux	B-Application
(	O
including	O
on	O
the	O
Raspberry	B-Operating_System
Pi	I-Operating_System
)	O
,	O
macOS	B-Application
and	O
Microsoft	B-Application
Windows	I-Application
platforms	O
.	O
</s>
<s>
It	O
is	O
based	O
on	O
APL2	O
,	O
with	O
extensions	O
to	O
support	O
object-oriented	B-Language
programming	I-Language
,	O
functional	B-Language
programming	I-Language
,	O
and	O
tacit	B-Application
programming	I-Application
.	O
</s>
<s>
In	O
1995	O
,	O
two	O
of	O
the	O
development	O
team	O
–	O
John	B-Application
Scholes	I-Application
and	O
Peter	O
Donnelly	O
–	O
were	O
awarded	O
the	O
Iverson	B-Language
Award	I-Language
for	O
their	O
work	O
on	O
the	O
interpreter	B-Application
.	O
</s>
<s>
Gitte	O
Christensen	O
and	O
Morten	O
Kromberg	O
were	O
joint	O
recipients	O
of	O
the	O
Iverson	B-Language
Award	I-Language
in	O
2016	O
.	O
</s>
<s>
NARS2000	O
is	O
an	O
open-source	B-Application
APL	B-General_Concept
interpreter	B-Application
written	O
by	O
Bob	O
Smith	O
,	O
a	O
prominent	O
APL	B-General_Concept
developer	B-Application
and	O
implementor	O
from	O
STSC	O
in	O
the	O
1970s	O
and	O
1980s	O
.	O
</s>
<s>
NARS2000	O
contains	O
advanced	O
features	O
and	O
new	O
datatypes	O
and	O
runs	O
natively	O
on	O
Microsoft	B-Application
Windows	I-Application
,	O
and	O
other	O
platforms	O
under	O
Wine	B-Application
.	O
</s>
<s>
APLX	B-Language
is	O
a	O
cross-platform	B-Operating_System
dialect	O
of	O
APL	B-General_Concept
,	O
based	O
on	O
APL2	O
and	O
with	O
several	O
extensions	O
,	O
which	O
was	O
first	O
released	O
by	O
British	O
company	O
MicroAPL	B-Language
in	O
2002	O
.	O
</s>
<s>
York	O
APL	B-General_Concept
was	O
developed	O
at	O
the	O
York	O
University	O
,	O
Ontario	O
around	O
1968	O
,	O
running	O
on	O
IBM	B-Application
360	I-Application
mainframes	O
.	O
</s>
<s>
One	O
notable	O
difference	O
between	O
it	O
and	O
APL	B-General_Concept
\360	O
was	O
that	O
it	O
defined	O
the	O
"	O
shape	O
"	O
( ρ	O
)	O
of	O
a	O
scalar	O
as	O
1	O
whereas	O
APL	B-General_Concept
\360	O
defined	O
it	O
as	O
the	O
more	O
mathematically	O
correct	O
0	O
—	O
this	O
made	O
it	O
easier	O
to	O
write	O
functions	O
that	O
acted	O
the	O
same	O
with	O
scalars	O
and	O
vectors	O
.	O
</s>
<s>
GNU	O
APL	B-General_Concept
is	O
a	O
free	O
implementation	O
of	O
Extended	O
APL	B-General_Concept
as	O
specified	O
in	O
ISO/IEC	O
13751:2001	O
and	O
is	O
thus	O
an	O
implementation	O
of	O
APL2	O
.	O
</s>
<s>
It	O
runs	O
on	O
Linux	B-Application
(	O
including	O
on	O
the	O
Raspberry	B-Operating_System
Pi	I-Operating_System
)	O
,	O
macOS	B-Application
,	O
several	O
BSD	O
dialects	O
,	O
and	O
on	O
Windows	O
(	O
either	O
using	O
Cygwin	B-Language
for	O
full	O
support	O
of	O
all	O
its	O
system	O
functions	O
or	O
as	O
a	O
native	O
64-bit	O
Windows	O
binary	O
with	O
some	O
of	O
its	O
system	O
functions	O
missing	O
)	O
.	O
</s>
<s>
GNU	O
APL	B-General_Concept
uses	O
Unicode	O
internally	O
and	O
can	O
be	O
scripted	O
.	O
</s>
<s>
It	O
was	O
written	O
by	O
Jürgen	O
Sauermann	O
.	O
</s>
<s>
Richard	O
Stallman	O
,	O
founder	O
of	O
the	B-Application
GNU	I-Application
Project	I-Application
,	O
was	O
an	O
early	O
adopter	O
of	O
APL	B-General_Concept
,	O
using	O
it	O
to	O
write	O
a	O
text	O
editor	O
as	O
a	O
high	O
school	O
student	O
in	O
the	O
summer	O
of	O
1969	O
.	O
</s>
<s>
APL	B-General_Concept
is	O
traditionally	O
an	O
interpreted	B-Application
language	I-Application
,	O
having	O
language	O
characteristics	O
such	O
as	O
weak	O
variable	O
typing	O
not	O
well	O
suited	O
to	O
compilation	B-Language
.	O
</s>
<s>
However	O
,	O
with	O
arrays	O
as	O
its	O
core	O
data	O
structure	O
it	O
provides	O
opportunities	O
for	O
performance	O
gains	O
through	O
parallelism	B-Operating_System
,	O
parallel	B-Operating_System
computing	I-Operating_System
,	O
massively	B-Operating_System
parallel	I-Operating_System
applications	O
,	O
and	O
very-large-scale	O
integration	O
(	O
VLSI	O
)	O
,	O
and	O
from	O
the	O
outset	O
APL	B-General_Concept
has	O
been	O
regarded	O
as	O
a	O
high-performance	O
language	O
–	O
for	O
example	O
,	O
it	O
was	O
noted	O
for	O
the	O
speed	O
with	O
which	O
it	O
could	O
perform	O
complicated	O
matrix	O
operations	O
"	O
because	O
it	O
operates	O
on	O
arrays	O
and	O
performs	O
operations	O
like	O
matrix	O
inversion	O
internally	O
"	O
.	O
</s>
<s>
Nevertheless	O
,	O
APL	B-General_Concept
is	O
rarely	O
purely	O
interpreted	O
and	O
compilation	B-Language
or	O
partial	O
compilation	B-Language
techniques	O
that	O
are	O
,	O
or	O
have	O
been	O
,	O
used	O
include	O
the	O
following	O
:	O
</s>
<s>
Most	O
APL	B-General_Concept
interpreters	B-Application
support	O
idiom	O
recognition	O
and	O
evaluate	O
common	O
idioms	O
as	O
single	O
operations	O
.	O
</s>
<s>
For	O
example	O
,	O
by	O
evaluating	O
the	O
idiom	O
BV/	O
⍳⍴A	O
as	O
a	O
single	O
operation	O
(	O
where	O
BV	O
is	O
a	O
Boolean	O
vector	B-Data_Structure
and	O
A	B-Application
is	I-Application
an	O
array	B-Application
)	O
,	O
the	O
creation	O
of	O
two	O
intermediate	O
arrays	O
is	O
avoided	O
.	O
</s>
<s>
Weak	O
typing	O
in	O
APL	B-General_Concept
means	O
that	O
a	O
name	O
may	O
reference	O
an	O
array	B-Application
(	O
of	O
any	O
datatype	O
)	O
,	O
a	O
function	O
or	O
an	O
operator	O
.	O
</s>
<s>
In	O
general	O
,	O
the	O
interpreter	B-Application
cannot	O
know	O
in	O
advance	O
which	O
form	O
it	O
will	O
be	O
and	O
must	O
therefore	O
perform	O
analysis	O
,	O
syntax	O
checking	O
etc	O
.	O
</s>
<s>
This	O
bytecode	O
can	O
also	O
be	O
optimised	O
using	O
compilation	B-Language
techniques	O
such	O
as	O
constant	O
folding	O
or	O
common	O
subexpression	O
elimination	O
.	O
</s>
<s>
The	O
interpreter	B-Application
will	O
execute	O
the	O
bytecode	O
when	O
present	O
and	O
when	O
any	O
assumptions	O
which	O
have	O
been	O
made	O
are	O
met	O
.	O
</s>
<s>
Dyalog	O
APL	B-General_Concept
includes	O
support	O
for	O
optimised	O
bytecode	O
.	O
</s>
<s>
Compilation	B-Language
of	O
APL	B-General_Concept
has	O
been	O
the	O
subject	O
of	O
research	O
and	O
experiment	O
since	O
the	O
language	O
first	O
became	O
available	O
;	O
the	O
first	O
compiler	B-Language
is	O
considered	O
to	O
be	O
the	O
Burroughs	O
APL-700	O
which	O
was	O
released	O
around	O
1971	O
.	O
</s>
<s>
In	O
order	O
to	O
be	O
able	O
to	O
compile	B-Language
APL	B-General_Concept
,	O
language	O
limitations	O
have	O
to	O
be	O
imposed	O
.	O
</s>
<s>
APEX	O
is	O
a	O
research	O
APL	B-General_Concept
compiler	B-Language
which	O
was	O
written	O
by	O
Robert	O
Bernecky	O
and	O
is	O
available	O
under	O
the	O
GNU	B-License
Public	I-License
License	I-License
.	O
</s>
<s>
The	O
STSC	O
APL	B-General_Concept
Compiler	B-Language
is	O
a	O
hybrid	O
of	O
a	O
bytecode	O
optimiser	O
and	O
a	O
compiler	B-Language
–	O
it	O
enables	O
compilation	B-Language
of	O
functions	O
to	O
machine	B-Language
code	I-Language
provided	O
that	O
its	O
sub-functions	O
and	O
globals	O
are	O
declared	O
,	O
but	O
the	O
interpreter	B-Application
is	O
still	O
used	O
as	O
a	O
runtime	B-Library
library	I-Library
and	O
to	O
execute	O
functions	O
which	O
do	O
not	O
meet	O
the	O
compilation	B-Language
requirements	O
.	O
</s>
<s>
APL	B-General_Concept
has	O
been	O
standardized	O
by	O
the	O
American	O
National	O
Standards	O
Institute	O
(	O
ANSI	O
)	O
working	O
group	O
X3J10	O
and	O
International	O
Organization	O
for	O
Standardization	O
(	O
ISO	O
)	O
and	O
International	O
Electrotechnical	O
Commission	O
(	O
IEC	O
)	O
,	O
ISO/IEC	O
Joint	O
Technical	O
Committee	O
1	O
Subcommittee	O
22	O
Working	O
Group	O
3	O
.	O
</s>
<s>
The	O
Core	O
APL	B-General_Concept
language	O
is	O
specified	O
in	O
ISO	O
8485:1989	O
,	O
and	O
the	O
Extended	O
APL	B-General_Concept
language	O
is	O
specified	O
in	O
ISO/IEC	O
13751:2001	O
.	O
</s>
