<s>
ALGOL	B-Language
68	I-Language
(	O
short	O
for	O
Algorithmic	B-Language
Language	I-Language
1968	I-Language
)	O
is	O
an	O
imperative	B-Application
programming	I-Application
language	I-Application
that	O
was	O
conceived	O
as	O
a	O
successor	O
to	O
the	O
ALGOL	B-Language
60	I-Language
programming	I-Language
language	I-Language
,	O
designed	O
with	O
the	O
goal	O
of	O
a	O
much	O
wider	O
scope	O
of	O
application	O
and	O
more	O
rigorously	O
defined	O
syntax	O
and	O
semantics	O
.	O
</s>
<s>
The	O
complexity	O
of	O
the	O
language	O
's	O
definition	O
,	O
which	O
runs	O
to	O
several	O
hundred	O
pages	O
filled	O
with	O
non-standard	O
terminology	O
,	O
made	O
compiler	B-Language
implementation	O
difficult	O
and	O
it	O
was	O
said	O
it	O
had	O
"	O
no	O
implementations	O
and	O
no	O
users	O
"	O
.	O
</s>
<s>
This	O
was	O
only	O
partly	O
true	O
;	O
ALGOL	B-Language
68	I-Language
did	O
find	O
use	O
in	O
several	O
niche	O
markets	O
,	O
notably	O
in	O
the	O
United	O
Kingdom	O
where	O
it	O
was	O
popular	O
on	O
International	O
Computers	O
Limited	O
(	O
ICL	O
)	O
machines	O
,	O
and	O
in	O
teaching	O
roles	O
.	O
</s>
<s>
Nevertheless	O
,	O
the	O
contributions	O
of	O
ALGOL	B-Language
68	I-Language
to	O
the	O
field	O
of	O
computer	B-General_Concept
science	I-General_Concept
have	O
been	O
deep	O
,	O
wide-ranging	O
and	O
enduring	O
,	O
although	O
many	O
of	O
these	O
contributions	O
were	O
only	O
publicly	O
identified	O
when	O
they	O
had	O
reappeared	O
in	O
subsequently	O
developed	O
programming	O
languages	O
.	O
</s>
<s>
Many	O
languages	O
were	O
developed	O
specifically	O
as	O
a	O
response	O
to	O
the	O
perceived	O
complexity	O
of	O
the	O
language	O
,	O
the	O
most	O
notable	O
being	O
Pascal	B-Application
,	O
or	O
were	O
reimplementations	O
for	O
specific	O
roles	O
,	O
like	O
Ada	B-Language
.	O
</s>
<s>
Many	O
languages	O
of	O
the	O
1970s	O
trace	O
their	O
design	O
specifically	O
to	O
ALGOL	B-Language
68	I-Language
,	O
selecting	O
some	O
features	O
while	O
abandoning	O
others	O
that	O
were	O
considered	O
too	O
complex	O
or	O
out-of-scope	O
for	O
given	O
roles	O
.	O
</s>
<s>
Among	O
these	O
is	O
the	O
language	O
C	B-Language
,	O
which	O
was	O
directly	O
influenced	O
by	O
ALGOL	B-Language
68	I-Language
,	O
especially	O
by	O
its	O
strong	O
typing	O
and	O
structures	O
.	O
</s>
<s>
Most	O
modern	O
languages	O
trace	O
at	O
least	O
some	O
of	O
their	O
syntax	O
to	O
either	O
C	B-Language
or	O
Pascal	B-Application
,	O
and	O
thus	O
directly	O
or	O
indirectly	O
to	O
ALGOL	B-Language
68	I-Language
.	O
</s>
<s>
ALGOL	B-Language
68	I-Language
features	O
include	O
expression-based	O
syntax	O
,	O
user-declared	O
types	O
and	O
structures/tagged	O
-unions	O
,	O
a	O
reference	O
model	O
of	O
variables	O
and	O
reference	O
parameters	O
,	O
string	O
,	O
array	O
and	O
matrix	O
slicing	O
,	O
and	O
concurrency	O
.	O
</s>
<s>
ALGOL	B-Language
68	I-Language
was	O
designed	O
by	O
the	O
International	O
Federation	O
for	O
Information	O
Processing	O
(	O
IFIP	O
)	O
IFIP	B-Language
Working	I-Language
Group	I-Language
2.1	I-Language
on	O
Algorithmic	B-Language
Languages	I-Language
and	O
Calculi	O
.	O
</s>
<s>
ALGOL	B-Language
68	I-Language
was	O
defined	O
using	O
a	O
formalism	O
,	O
a	O
two-level	O
formal	O
grammar	O
,	O
invented	O
by	O
Adriaan	O
van	O
Wijngaarden	O
.	O
</s>
<s>
Van	B-Application
Wijngaarden	I-Application
grammars	I-Application
use	O
a	O
context-free	O
grammar	O
to	O
generate	O
an	O
infinite	O
set	O
of	O
productions	O
that	O
will	O
recognize	O
a	O
particular	O
ALGOL	B-Language
68	I-Language
program	O
;	O
notably	O
,	O
they	O
are	O
able	O
to	O
express	O
the	O
kind	O
of	O
requirements	O
that	O
in	O
many	O
other	O
programming	O
language	O
technical	O
standards	O
are	O
labelled	O
semantics	O
,	O
and	O
must	O
be	O
expressed	O
in	O
ambiguity-prone	O
natural	O
language	O
prose	O
,	O
and	O
then	O
implemented	O
in	O
compilers	B-Language
as	O
ad	O
hoc	O
code	O
attached	O
to	O
the	O
formal	O
language	O
parser	O
.	O
</s>
<s>
The	O
main	O
aims	O
and	O
principles	O
of	O
design	O
of	O
ALGOL	B-Language
68	I-Language
:	O
</s>
<s>
ALGOL	B-Language
68	I-Language
has	O
been	O
criticized	O
,	O
most	O
prominently	O
by	O
some	O
members	O
of	O
its	O
design	O
committee	O
such	O
as	O
C	B-Language
.	O
A	O
.	O
R	O
.	O
Hoare	O
and	O
Edsger	O
Dijkstra	O
,	O
for	O
abandoning	O
the	O
simplicity	O
of	O
ALGOL	B-Language
60	I-Language
,	O
becoming	O
a	O
vehicle	O
for	O
complex	O
or	O
overly	O
general	O
ideas	O
,	O
and	O
doing	O
little	O
to	O
make	O
the	O
compiler	B-Language
writer	O
's	O
task	O
easier	O
,	O
in	O
contrast	O
to	O
deliberately	O
simple	O
contemporaries	O
(	O
and	O
competitors	O
)	O
such	O
as	O
C	B-Language
,	O
S-algol	B-Language
and	O
Pascal	B-Application
.	O
</s>
<s>
In	O
1970	O
,	O
ALGOL	B-General_Concept
68-R	I-General_Concept
became	O
the	O
first	O
working	O
compiler	B-Language
for	O
ALGOL	B-Language
68	I-Language
.	O
</s>
<s>
C.f.	O
</s>
<s>
Though	O
European	O
defence	O
agencies	O
(	O
in	O
Britain	O
Royal	O
Signals	O
and	O
Radar	O
Establishment	O
(	O
RSRE	O
)	O
)	O
promoted	O
the	O
use	O
of	O
ALGOL	B-Language
68	I-Language
for	O
its	O
expected	O
security	O
advantages	O
,	O
the	O
American	O
side	O
of	O
the	O
NATO	O
alliance	O
decided	O
to	O
develop	O
a	O
different	O
project	O
,	O
the	O
language	O
Ada	B-Language
,	O
making	O
its	O
use	O
obligatory	O
for	O
US	O
defense	O
contracts	O
.	O
</s>
<s>
ALGOL	B-Language
68	I-Language
also	O
had	O
a	O
notable	O
influence	O
in	O
the	O
Soviet	O
Union	O
,	O
details	O
of	O
which	O
can	O
be	O
found	O
in	O
Andrey	O
Ershov	O
's	O
2014	O
paper	O
:	O
"	O
ALGOL	B-Language
68	I-Language
and	O
Its	O
Impact	O
on	O
the	O
USSR	O
and	O
Russian	O
Programming	O
"	O
,	O
and	O
"	O
Алгол	O
68	O
и	O
его	O
влияние	O
на	O
программирование	O
в	O
СССР	O
и	O
России	O
"	O
.	O
</s>
<s>
Steve	O
Bourne	O
,	O
who	O
was	O
on	O
the	O
ALGOL	B-Language
68	I-Language
revision	O
committee	O
,	O
took	O
some	O
of	O
its	O
ideas	O
to	O
his	O
Bourne	B-Device
shell	I-Device
(	O
and	O
thereby	O
,	O
to	O
descendant	O
Unix	B-Application
shells	I-Application
such	O
as	O
Bash	B-Operating_System
)	O
and	O
to	O
C	B-Language
(	O
and	O
thereby	O
to	O
descendants	O
such	O
as	O
C++	B-Language
)	O
.	O
</s>
<s>
The	O
complete	O
history	O
of	O
the	O
project	O
can	O
be	O
found	O
in	O
C	B-Language
.	O
H	O
.	O
Lindsey	O
's	O
A	O
History	O
of	O
ALGOL	B-Language
68	I-Language
.	O
</s>
<s>
For	O
a	O
full-length	O
treatment	O
of	O
the	O
language	O
,	O
see	O
"	O
Programming	O
ALGOL	B-Language
68	I-Language
Made	O
Easy	O
"	O
by	O
Dr.	O
Sian	O
Mountbatten	O
,	O
or	O
"	O
Learning	O
ALGOL	B-Language
68	I-Language
Genie	O
"	O
by	O
Marcel	O
van	O
der	O
Veer	O
which	O
includes	O
the	O
Revised	O
Report	O
.	O
</s>
<s>
ALGOL	B-Language
68	I-Language
,	O
as	O
the	O
name	O
implies	O
,	O
is	O
a	O
follow-on	O
to	O
the	O
ALGOL	B-Language
language	I-Language
that	O
was	O
first	O
formalized	O
in	O
1960	O
.	O
</s>
<s>
That	O
same	O
year	O
the	O
International	O
Federation	O
for	O
Information	O
Processing	O
(	O
IFIP	O
)	O
formed	O
and	O
started	O
the	O
Working	O
Group	O
on	O
ALGOL	B-Language
,	O
or	O
WG2.1	O
.	O
</s>
<s>
This	O
group	O
released	O
an	O
updated	O
ALGOL	B-Language
60	I-Language
specification	O
in	O
Rome	O
in	O
April	O
1962	O
.	O
</s>
<s>
At	O
a	O
follow-up	O
meeting	O
in	O
March	O
1964	O
,	O
it	O
was	O
agreed	O
that	O
the	O
group	O
should	O
begin	O
work	O
on	O
two	O
follow-on	O
standards	O
,	O
ALGOL	B-Language
X	I-Language
which	O
would	O
be	O
a	O
redefinition	O
of	O
the	O
language	O
with	O
some	O
additions	O
,	O
and	O
an	O
ALGOL	B-Language
Y	I-Language
,	O
which	O
would	O
have	O
the	O
ability	O
to	O
modify	O
its	O
own	O
programs	O
in	O
the	O
style	O
of	O
the	O
language	O
LISP	B-Language
.	O
</s>
<s>
The	O
first	O
meeting	O
of	O
the	O
ALGOL	B-Language
X	I-Language
group	O
was	O
held	O
in	O
Princeton	O
University	O
in	O
May	O
1965	O
.	O
</s>
<s>
A	O
report	O
of	O
the	O
meeting	O
noted	O
two	O
broadly	O
supported	O
themes	O
,	O
the	O
introduction	O
of	O
strong	O
typing	O
and	O
interest	O
in	O
Euler	B-Language
's	I-Language
concepts	O
of	O
'	O
trees	O
 '	O
or	O
'	O
lists	O
 '	O
for	O
handling	O
collections	O
.	O
</s>
<s>
At	O
the	O
second	O
meeting	O
in	O
October	O
in	O
France	O
,	O
three	O
formal	O
proposals	O
were	O
presented	O
,	O
Niklaus	O
Wirth	O
's	O
ALGOL	B-Language
W	I-Language
along	O
with	O
comments	O
about	O
record	O
structures	O
by	O
C.A.R.	O
</s>
<s>
The	O
latter	O
,	O
written	O
in	O
almost	O
indecipherable	O
"	O
W-Grammar	B-Application
"	O
,	O
proved	O
to	O
be	O
a	O
decisive	O
shift	O
in	O
the	O
evolution	O
of	O
the	O
language	O
.	O
</s>
<s>
The	O
meeting	O
closed	O
with	O
an	O
agreement	O
that	O
van	O
Wijngaarden	O
would	O
re-write	O
the	O
Wirth/Hoare	O
submission	O
using	O
his	O
W-Grammar	B-Application
.	O
</s>
<s>
Wirth	O
then	O
implemented	O
their	O
current	O
definition	O
as	O
ALGOL	B-Language
W	I-Language
.	O
</s>
<s>
At	O
the	O
next	O
meeting	O
in	O
Warsaw	B-Application
in	O
October	O
1966	O
,	O
there	O
was	O
an	O
initial	O
report	O
from	O
the	O
I/O	O
Subcommittee	O
who	O
had	O
met	O
at	O
the	O
Oak	O
Ridge	O
National	O
Laboratory	O
and	O
the	O
University	O
of	O
Illinois	O
but	O
had	O
not	O
yet	O
made	O
much	O
progress	O
.	O
</s>
<s>
The	O
two	O
proposals	O
from	O
the	O
previous	O
meeting	O
were	O
again	O
explored	O
,	O
and	O
this	O
time	O
a	O
new	O
debate	O
emerged	O
about	O
the	O
use	O
of	O
pointers	O
;	O
ALGOL	B-Language
W	I-Language
used	O
them	O
only	O
to	O
refer	O
to	O
records	O
,	O
while	O
van	O
Wijngaarden	O
's	O
version	O
could	O
point	O
to	O
any	O
object	O
.	O
</s>
<s>
To	O
add	O
confusion	O
,	O
John	O
McCarthy	O
presented	O
a	O
new	O
proposal	O
for	O
operator	O
overloading	B-Application
and	O
the	O
ability	O
to	O
string	O
together	O
and	O
or	O
constructs	O
,	O
and	O
Klaus	O
Samelson	O
wanted	O
to	O
allow	O
anonymous	B-General_Concept
functions	I-General_Concept
.	O
</s>
<s>
The	O
confusion	O
continued	O
through	O
what	O
was	O
supposed	O
to	O
be	O
the	O
ALGOL	B-Language
Y	I-Language
meeting	O
in	O
Zandvoort	O
in	O
May	O
1967	O
.	O
</s>
<s>
The	O
resulting	O
paper	O
,	O
"	O
ALGOL	B-Language
68	I-Language
with	O
fewer	O
tears	O
"	O
,	O
was	O
widely	O
circulated	O
.	O
</s>
<s>
It	O
was	O
supposed	O
to	O
discuss	O
the	O
release	O
of	O
compilers	B-Language
and	O
other	O
issues	O
,	O
but	O
instead	O
devolved	O
into	O
a	O
discussion	O
on	O
the	O
language	O
.	O
</s>
<s>
By	O
this	O
point	O
Naur	O
,	O
Hoare	O
,	O
and	O
Wirth	O
had	O
left	O
the	O
effort	O
,	O
and	O
several	O
more	O
were	O
threatening	O
to	O
do	B-Language
so	O
.	O
</s>
<s>
The	O
effort	O
took	O
five	O
years	O
,	O
burned	O
out	O
many	O
of	O
the	O
greatest	O
names	O
in	O
computer	B-General_Concept
science	I-General_Concept
,	O
and	O
on	O
several	O
occasions	O
became	O
deadlocked	O
over	O
issues	O
both	O
in	O
the	O
definition	O
and	O
the	O
group	O
as	O
a	O
whole	O
.	O
</s>
<s>
Hoare	O
released	O
a	O
"	O
Critique	O
of	O
ALGOL	B-Language
68	I-Language
"	O
almost	O
immediately	O
,	O
which	O
has	O
been	O
widely	O
referenced	O
in	O
many	O
works	O
.	O
</s>
<s>
Wirth	O
went	O
on	O
to	O
further	O
develop	O
the	O
ALGOL	B-Language
W	I-Language
concept	O
and	O
released	O
this	O
as	O
Pascal	B-Application
in	O
1970	O
.	O
</s>
<s>
The	O
first	O
implementation	O
of	O
the	O
standard	O
,	O
based	O
on	O
the	O
late-1968	O
draft	O
Report	O
,	O
was	O
introduced	O
by	O
the	O
Royal	O
Radar	O
Establishment	O
in	O
the	O
UK	O
as	O
ALGOL	B-General_Concept
68-R	I-General_Concept
in	O
July	O
1970	O
.	O
</s>
<s>
This	O
had	O
a	O
significant	O
advantage	O
that	O
it	O
allowed	O
the	O
compiler	B-Language
to	O
be	O
one-pass	O
,	O
as	O
space	O
for	O
the	O
variables	O
in	O
the	O
activation	O
record	O
was	O
set	O
aside	O
before	O
it	O
was	O
used	O
.	O
</s>
<s>
Further	O
,	O
68-R	O
eliminated	O
the	O
explicit	O
parallel	B-Operating_System
processing	I-Operating_System
commands	O
based	O
on	O
PAR	O
.	O
</s>
<s>
A	O
version	O
similar	O
to	O
68-R	O
was	O
introduced	O
from	O
Carnegie	O
Mellon	O
University	O
in	O
1976	O
as	O
68S	O
,	O
and	O
was	O
again	O
a	O
one-pass	O
compiler	B-Language
based	O
on	O
various	O
simplifications	O
of	O
the	O
original	O
and	O
intended	O
for	O
use	O
on	O
smaller	O
machines	O
like	O
the	O
DEC	B-Device
PDP-11	I-Device
.	O
</s>
<s>
Lindsey	O
released	O
a	O
version	O
for	O
small	O
machines	O
including	O
the	O
IBM	B-Device
PC	I-Device
in	O
1984	O
.	O
</s>
<s>
Three	O
open	O
source	O
Algol	B-Language
68	I-Language
implementations	O
are	O
known	O
:	O
</s>
<s>
algol68toc	O
,	O
an	O
open-source	B-Application
software	I-Application
port	O
of	O
ALGOL	B-General_Concept
68RS	I-General_Concept
.	O
</s>
<s>
experimental	O
Algol68	B-Language
frontend	O
for	O
GCC	O
,	O
written	O
by	O
Jose	O
E	O
.	O
Marchesi	O
.	O
</s>
<s>
Year	O
Event	O
Contributor	O
March	O
1959	O
ALGOL	B-Language
Bulletin	I-Language
Issue	O
1	O
(	O
First	O
)	O
Peter	O
Naur	O
/	O
ACM	O
February	O
1968	O
Draft	O
Report(DR )	O
Published	O
IFIP	B-Language
Working	I-Language
Group	I-Language
2.1	I-Language
March	O
1968	O
Algol	B-Language
68	I-Language
Final	O
Reportr0	O
Presented	O
at	O
Munich	O
Meeting	O
IFIP	B-Language
Working	I-Language
Group	I-Language
2.1	I-Language
June	O
1968	O
Meeting	O
in	O
Tirrenia	O
,	O
Italy	O
IFIP	B-Language
Working	I-Language
Group	I-Language
2.1	I-Language
Aug	O
1968	O
Meeting	O
in	O
North	O
Berwick	O
,	O
Scotland	O
IFIP	B-Language
Working	I-Language
Group	I-Language
2.1	I-Language
December	O
1968	O
ALGOL	B-Language
68	I-Language
Final	O
Reportr0	O
Presented	O
at	O
Munich	O
Meeting	O
IFIP	B-Language
Working	I-Language
Group	I-Language
2.1	I-Language
April	O
1970	O
ALGOL	O
68-R(R )	O
under	O
GEORGE	B-General_Concept
3	I-General_Concept
on	O
an	O
ICL	O
1907F	B-Device
Royal	O
Signals	O
and	O
Radar	O
Est	O
.	O
</s>
<s>
July	O
1970	O
ALGOL	B-Language
68	I-Language
for	O
the	O
Dartmouth	O
Time	O
Sharing	O
SystemSidney	O
Marshall	O
,	O
"	O
ALGOL	B-Language
68	I-Language
Implementation	O
"	O
,	O
Proceedings	O
of	O
the	O
IFIP	O
Working	O
Conference	O
on	O
ALGOL	B-Language
68	I-Language
Implementation	O
,	O
Munich	O
,	O
July	O
20	O
–	O
24	O
,	O
1970	O
,	O
J	O
.	O
E	O
.	O
L	O
.	O
Peck	O
,	O
editor	O
,	O
North	O
Holland	O
,	O
pages	O
239	O
–	O
243.Sidney	O
Marshall	O
,	O
On	O
the	O
implementation	O
of	O
ALGOL	B-Language
68	I-Language
,	O
PhD	O
Thesis	O
,	O
Dartmouth	O
College	O
,	O
1972	O
.	O
</s>
<s>
Sidney	O
Marshall	O
September	O
1973	O
Algol	B-Language
68	I-Language
Revised	O
ReportAlgol	O
68	O
Revised	O
Reportr1	O
Published	O
IFIP	B-Language
Working	I-Language
Group	I-Language
2.1	I-Language
1975	O
ALGOL	O
68C(C )	O
–	O
transportable	O
compiler	B-Language
(	O
zcode	B-General_Concept
VM	B-Architecture
)	O
S	O
.	O
Bourne	O
,	O
Andrew	O
Birrell	O
,	O
and	O
Michael	O
Guy	O
June	O
1975	O
G	O
.	O
E	O
.	O
Hedrick	O
and	O
Alan	O
Robertson	O
.	O
</s>
<s>
The	O
Oklahoma	O
State	O
ALGOL	B-Language
68	I-Language
Subset	O
Compiler	B-Language
.	O
</s>
<s>
1975	O
International	O
Conference	O
on	O
ALGOL	B-Language
68	I-Language
.	O
</s>
<s>
June	O
1977	O
Strathclyde	O
ALGOL	B-Language
68	I-Language
conference	O
,	O
Scotland	O
ACM	O
May	O
1978	O
Proposals	O
for	O
ALGOL	B-Language
H	O
–	O
A	O
Superlanguage	O
of	O
ALGOL	B-Language
68	I-Language
A	O
.	O
P	O
.	O
Black	O
,	O
V	O
.	O
J	O
.	O
Rayward-Smith	O
1984	O
Full	O
ALGOL	B-Language
68S(S )	O
compiler	B-Language
for	O
Sun	O
,	O
SPARC	B-Architecture
,	O
and	O
PCs	O
C	B-Language
.	O
H	O
.	O
Lindsey	O
et	O
al	O
,	O
Manchester	O
August	O
1988	O
ALGOL	B-Language
Bulletin	I-Language
Issue	O
52	O
(	O
last	O
)	O
Ed	O
.	O
</s>
<s>
March	O
1968	O
:	O
Draft	O
Report	O
on	O
the	O
Algorithmic	B-Language
Language	I-Language
ALGOL	B-Language
68	I-Language
–	O
Edited	O
by	O
:	O
Adriaan	O
van	O
Wijngaarden	O
,	O
Barry	O
J	O
.	O
Mailloux	O
,	O
John	O
Peck	O
and	O
Cornelis	O
H	O
.	O
A	O
.	O
Koster	O
.	O
</s>
<s>
October	O
1968	O
:	O
Penultimate	O
Draft	O
Report	O
on	O
the	O
Algorithmic	B-Language
Language	I-Language
ALGOL	B-Language
68	I-Language
–	O
Chapters	O
1-9	O
Chapters	O
10-12	O
–	O
Edited	O
by	O
:	O
A	O
.	O
van	O
Wijngaarden	O
,	O
B.J.	O
</s>
<s>
Mailloux	O
,	O
J	O
.	O
E	O
.	O
L	O
.	O
Peck	O
and	O
C	B-Language
.	O
H	O
.	O
A	O
.	O
Koster	O
.	O
</s>
<s>
December	O
1968	O
:	O
Report	O
on	O
the	O
Algorithmic	B-Language
Language	I-Language
ALGOL	B-Language
68	I-Language
–	O
Offprint	O
from	O
Numerische	O
Mathematik	O
,	O
14	O
,	O
79-218	O
(	O
1969	O
)	O
;	O
Springer-Verlag	O
.	O
</s>
<s>
–	O
Edited	O
by	O
:	O
A	O
.	O
van	O
Wijngaarden	O
,	O
B	O
.	O
J	O
.	O
Mailloux	O
,	O
J	O
.	O
E	O
.	O
L	O
.	O
Peck	O
and	O
C	B-Language
.	O
H	O
.	O
A	O
.	O
Koster	O
.	O
</s>
<s>
March	O
1970	O
:	O
Minority	O
report	O
,	O
ALGOL	B-Language
Bulletin	I-Language
AB31.1.1	O
-	O
signed	O
by	O
Edsger	O
Dijkstra	O
,	O
Fraser	O
Duncan	O
,	O
Jan	O
Garwick	O
,	O
Tony	O
Hoare	O
,	O
Brian	O
Randell	O
,	O
Gerhard	O
Seegmüller	O
,	O
Wlad	O
Turski	O
,	O
and	O
Mike	O
Woodger	O
.	O
</s>
<s>
September	O
1973	O
:	O
Revised	O
Report	O
on	O
the	O
Algorithmic	B-Language
Language	I-Language
Algol	B-Language
68	I-Language
–	O
Springer-Verlag	O
1976	O
–	O
Edited	O
by	O
:	O
A	O
.	O
van	O
Wijngaarden	O
,	O
B	O
.	O
Mailloux	O
,	O
J	O
.	O
Peck	O
,	O
K	O
.	O
Koster	O
,	O
Michel	O
Sintzoff	O
,	O
Charles	O
H	O
.	O
Lindsey	O
,	O
Lambert	O
Meertens	O
and	O
Richard	O
G	O
.	O
Fisker	O
.	O
</s>
<s>
other	O
WG	O
2.1	O
members	O
active	O
in	O
ALGOL	B-Language
68	I-Language
design	O
:	O
Friedrich	O
L	O
.	O
Bauer	O
•	O
Hans	O
Bekic	O
•	O
Gerhard	O
Goos	O
•	O
Peter	O
Zilahy	O
Ingerman	O
•	O
Peter	O
Landin	O
•	O
John	O
McCarthy	O
•	O
Jack	O
Merner	O
•	O
Peter	O
Naur	O
•	O
Manfred	O
Paul	O
•	O
Willem	O
van	O
der	O
Poel	O
•	O
Doug	O
Ross	O
•	O
Klaus	O
Samelson	O
•	O
Niklaus	O
Wirth	O
•	O
Nobuo	O
Yoneda	O
.	O
</s>
<s>
1984	O
:	O
TC	O
97	O
considered	O
ALGOL	B-Language
68	I-Language
for	O
standardisation	O
as	O
"	O
New	O
Work	O
Item	O
"	O
TC97/N1642	O
.	O
</s>
<s>
West	O
Germany	O
,	O
Belgium	O
,	O
Netherlands	O
,	O
USSR	O
and	O
Czechoslovakia	O
willing	O
to	O
participate	O
in	O
preparing	O
the	O
standard	O
but	O
the	O
USSR	O
and	O
Czechoslovakia	O
"	O
were	O
not	O
the	O
right	O
kinds	O
of	O
member	O
of	O
the	O
right	O
ISO	O
committees	O
"	O
and	O
Algol	B-Language
68	I-Language
's	O
ISO	O
standardisation	O
stalled	O
.	O
</s>
<s>
1988	O
:	O
Subsequently	O
ALGOL	B-Language
68	I-Language
became	O
one	O
of	O
the	O
GOST	B-Algorithm
standards	O
in	O
Russia	O
.	O
</s>
<s>
CHANNEL	O
,	O
FILE	O
,	O
FORMAT	O
,	O
STRUCT	B-Language
,	O
UNION	O
,	O
</s>
<s>
FOR	O
~	O
FROM	O
~	O
TO	O
~	O
BY	O
~	O
WHILE	O
~	O
DO	B-Language
~	O
OD	O
,	O
</s>
<s>
PAR	O
BEGIN	O
~	O
END	O
"	O
(	O
~	O
)	O
"	O
,	O
GO	B-Application
TO	O
,	O
GOTO	O
,	O
EXIT	O
"	O
□	O
"	O
r0	O
.	O
</s>
<s>
The	O
technical	O
term	O
enclosed	O
clause	O
unifies	O
some	O
of	O
the	O
inherently	O
bracketing	O
constructs	O
known	O
as	O
block	O
,	O
do	B-Language
statement	O
,	O
switch	O
statement	O
in	O
other	O
contemporary	O
languages	O
.	O
</s>
<s>
(	O
IF	O
~	O
THEN	O
~	O
ELSE	O
~	O
FI	O
,	O
CASE	O
~	O
IN	O
~	O
OUT	O
~	O
ESAC	O
,	O
FOR	O
~	O
WHILE	O
~	O
DO	B-Language
~	O
OD	O
)	O
.	O
</s>
<s>
This	O
Guarded	O
Command	O
syntax	O
was	O
reused	O
by	O
Stephen	O
Bourne	O
in	O
the	O
common	O
Unix	B-Application
Bourne	B-Device
shell	I-Device
.	O
</s>
<s>
The	O
basic	O
data	O
types	O
(	O
called	O
modes	O
in	O
Algol	B-Language
68	I-Language
parlance	O
)	O
are	O
real	O
,	O
int	O
,	O
compl	O
(	O
complex	O
number	O
)	O
,	O
bool	O
,	O
char	O
,	O
bits	O
and	O
bytes	O
.	O
</s>
<s>
Furthermore	O
,	O
instead	O
of	O
defining	O
both	O
float	O
and	O
double	O
,	O
or	O
int	O
and	O
long	O
and	O
short	O
,	O
etc.	O
,	O
ALGOL	B-Language
68	I-Language
provides	O
modifiers	O
,	O
so	O
that	O
the	O
presently	O
common	O
double	O
would	O
be	O
written	O
as	O
LONG	O
REAL	O
or	O
LONG	O
LONG	O
REAL	O
instead	O
,	O
for	O
example	O
.	O
</s>
<s>
SEMA	O
–	O
a	O
SEMAphore	B-Operating_System
which	O
can	O
be	O
initialised	O
with	O
the	O
OPerator	O
LEVEL	O
.	O
</s>
<s>
For	O
some	O
examples	O
,	O
see	O
Comparison	B-Language
of	I-Language
ALGOL	I-Language
68	I-Language
and	I-Language
C++	I-Language
.	O
</s>
<s>
which	O
is	O
similar	O
to	O
TYPEDEF	O
in	O
C/C	O
++	O
and	O
TYPE	O
in	O
Pascal	B-Application
:	O
</s>
<s>
This	O
is	O
similar	O
to	O
the	O
following	O
C	B-Language
code	O
:	O
</s>
<s>
For	O
ALGOL	B-Language
68	I-Language
,	O
only	O
the	O
NEWMODE	O
mode-indication	O
appears	O
to	O
the	O
left	O
of	O
the	O
equals	O
symbol	O
,	O
and	O
most	O
notably	O
the	O
construction	O
is	O
made	O
,	O
and	O
can	O
be	O
read	O
,	O
from	O
left	O
to	O
right	O
without	O
regard	O
to	O
priorities	O
.	O
</s>
<s>
Also	O
,	O
the	O
lower	O
bound	O
of	O
Algol	B-Language
68	I-Language
arrays	B-Data_Structure
is	O
one	O
by	O
default	O
,	O
but	O
can	O
be	O
any	O
integer	O
from	O
-max	O
int	O
to	O
max	O
int	O
.	O
</s>
<s>
ALGOL	B-Language
68	I-Language
has	O
a	O
hierarchy	O
of	O
contexts	O
which	O
determine	O
the	O
kind	O
of	O
coercions	O
available	O
at	O
a	O
particular	O
point	O
in	O
the	O
program	O
.	O
</s>
<s>
REF	O
REF	O
REF	O
REF	O
STRUCT	B-Language
to	O
REF	O
STRUCTbgcolor	O
=	O
"	O
#5555ff	O
"	O
style	O
=	O
"	O
color	O
:	O
#ffffff	O
;	O
"	O
The	O
LHS	O
of	O
assignments	O
,	O
as	O
"	O
~	O
"	O
in	O
:	O
~	O
:=	O
...	O
</s>
<s>
Pragmats	O
are	O
directives	O
in	O
the	O
program	O
,	O
typically	O
hints	O
to	O
the	O
compiler	B-Language
;	O
in	O
newer	O
languages	O
these	O
are	O
called	O
"	O
pragmas	O
"	O
(	O
no	O
'	O
t	O
 '	O
)	O
.	O
</s>
<s>
Normally	O
,	O
comments	O
cannot	O
be	O
nested	O
in	O
ALGOL	B-Language
68	I-Language
.	O
</s>
<s>
ALGOL	B-Language
68	I-Language
being	O
an	O
expression-oriented	O
programming	O
language	O
,	O
the	O
value	O
returned	O
by	O
an	O
assignment	O
statement	O
is	O
a	O
reference	O
to	O
the	O
destination	O
.	O
</s>
<s>
Thus	O
,	O
the	O
following	O
is	O
valid	O
ALGOL	B-Language
68	I-Language
code	O
:	O
</s>
<s>
This	O
notion	O
is	O
present	O
in	O
C	B-Language
and	O
Perl	B-Language
,	O
among	O
others	O
.	O
</s>
<s>
Note	O
that	O
as	O
in	O
earlier	O
languages	O
such	O
as	O
Algol	B-Language
60	I-Language
and	O
FORTRAN	B-Application
,	O
spaces	O
are	O
allowed	O
in	O
identifiers	O
,	O
so	O
that	O
half	O
pi	O
is	O
a	O
single	O
identifier	O
(	O
thus	O
avoiding	O
the	O
underscores	O
versus	O
camel	O
case	O
versus	O
all	O
lower-case	O
issues	O
)	O
.	O
</s>
<s>
As	O
another	O
example	O
,	O
to	O
express	O
the	O
mathematical	O
idea	O
of	O
a	O
sum	O
of	O
f(i )	O
from	O
i	O
=	O
1	O
to	O
n	O
,	O
the	O
following	O
ALGOL	B-Language
68	I-Language
integer	O
expression	O
suffices	O
:	O
</s>
<s>
A	O
block	O
of	O
code	O
returns	O
the	O
value	O
of	O
the	O
last	O
expression	O
it	O
evaluated	O
;	O
this	O
idea	O
is	O
present	O
in	O
Lisp	B-Language
,	O
among	O
other	O
languages	O
.	O
</s>
<s>
Algol68	B-Language
allowed	O
the	O
switch	O
to	O
be	O
of	O
either	B-Language
type	I-Language
INT	O
or	O
(	O
uniquely	O
)	O
UNION	O
.	O
</s>
<s>
c.f.	O
</s>
<s>
do	B-Language
loop	I-Language
clause	O
:	O
</s>
<s>
only	O
the	O
DO	B-Language
~	O
OD	O
portion	O
was	O
compulsory	O
,	O
in	O
which	O
case	O
the	O
loop	O
will	O
iterate	O
indefinitely	O
.	O
</s>
<s>
thus	O
the	O
clause	O
TO	O
100	O
DO	B-Language
~	O
OD	O
,	O
will	O
iterate	O
only	O
100	O
times	O
.	O
</s>
<s>
the	O
WHILE	O
"	O
syntactic	O
element	O
"	O
allowed	O
a	O
programmer	O
to	O
break	O
from	O
a	O
FOR	B-Language
loop	I-Language
early	O
.	O
</s>
<s>
Subsequent	O
"	O
extensions	O
"	O
to	O
the	O
standard	O
Algol68	B-Language
allowed	O
the	O
TO	O
syntactic	O
element	O
to	O
be	O
replaced	O
with	O
UPTO	O
and	O
DOWNTO	O
to	O
achieve	O
a	O
small	O
optimisation	O
.	O
</s>
<s>
The	O
same	O
compilers	B-Language
also	O
incorporated	O
:	O
</s>
<s>
UNTIL(C )	O
–	O
for	O
late	O
loop	O
termination	O
.	O
</s>
<s>
FOREACH(S )	O
–	O
for	O
working	O
on	O
arrays	B-Data_Structure
in	O
parallel	B-Operating_System
.	O
</s>
<s>
ALGOL	B-Language
68	I-Language
supports	O
arrays	B-Data_Structure
with	O
any	O
number	O
of	O
dimensions	O
,	O
and	O
it	O
allows	O
for	O
the	O
slicing	O
of	O
whole	O
or	O
partial	O
rows	O
or	O
columns	O
.	O
</s>
<s>
(	O
VECTOR	O
out	O
;	O
FOR	O
i	O
FROM	O
⌊a	O
TO	O
⌈a	O
DO	B-Language
out[i]	O
:=	O
a[i]+b[i]	O
OD	O
;	O
out	O
)	O
;	O
</s>
<s>
ALGOL	B-Language
68	I-Language
supports	O
multiple	O
field	O
structures	O
(	O
STRUCT	B-Language
)	O
and	O
united	B-Language
modes	I-Language
.	O
</s>
<s>
LIST	O
=	O
STRUCT	B-Language
(	O
NODE	O
val	O
,	O
REF	O
LIST	O
next	O
)	O
;	O
</s>
<s>
print( ( 	O
"	O
compl	O
:	O
"	O
,	O
c	B-Language
)	O
)	O
,	O
</s>
<s>
(	O
COMPL	O
c	B-Language
)	O
:	O
print( ( 	O
"	O
compl	O
:	O
"	O
,	O
c	B-Language
)	O
)	O
,	O
</s>
<s>
This	O
simplicity	O
of	O
code	O
was	O
unachievable	O
in	O
ALGOL	B-Language
68	I-Language
's	O
predecessor	O
ALGOL	B-Language
60	I-Language
.	O
</s>
<s>
The	O
programmer	O
may	O
define	O
new	O
operators	O
and	O
both	O
those	O
and	O
the	O
pre-defined	O
ones	O
may	O
be	O
overloaded	B-Application
and	O
their	O
priorities	O
may	O
be	O
changed	O
by	O
the	O
coder	O
.	O
</s>
<s>
FOR	O
i	O
FROM	O
LWB	O
a	O
+	O
1	O
TO	O
UPB	O
a	O
DO	B-Language
(	O
a[i]>out	O
|	O
out:=a[i]	O
)	O
OD	O
;	O
</s>
<s>
PRIOrity(Tertiary )	O
Algol68	B-Language
"	O
Worthy	O
characters	O
"	O
r0&r1+Algol68r0&r1+Algol68C	O
,	O
G+Algol68r0	O
10	O
NOT	O
~	O
,	O
UP	O
,	O
DOWN	O
,	O
LWB	O
,	O
UPB	O
,	O
</s>
<s>
PRIOrity(Tertiary )	O
Algol68	B-Language
"	O
Worthy	O
characters	O
"	O
r0&r1+Algol68r0&r1+Algol68C	O
,	O
G+Algol68r09	O
+*	O
,	O
I	O
+×	O
,	O
⊥	O
!	O
8	O
SHL	O
,	O
SHR	O
,	O
**	O
,	O
UP	O
,	O
DOWN	O
,	O
LWB	O
,	O
UPB	O
↑	O
,	O
↓	O
,	O
⌊	O
,	O
⌈	O
××	O
,	O
^	O
,	O
LWS	O
,	O
UPS	O
,	O
⎩	O
,	O
⎧7	O
*	O
,	O
/	O
,	O
%	O
,	O
OVER	O
,	O
%*	O
,	O
MOD	O
,	O
ELEM	O
×	O
,	O
÷	O
,	O
÷×	O
,	O
÷*	O
,	O
%×	O
,	O
□	O
÷	O
:6	O
-	O
,	O
+	O
5	O
<, LT, <=, LE,  >=, GE, >	O
,	O
GT	O
≤	O
,	O
≥	O
4	O
EQ	O
=	O
,	O
NE	O
~	O
=	O
/	O
=	O
≠	O
,	O
¬	O
=	O
3	O
&	O
,	O
AND	O
∧	O
/	O
\2	O
OR	O
∨	O
\/1	O
MINUSAB	O
,	O
PLUSAB	O
,	O
TIMESAB	O
,	O
DIVAB	O
,	O
OVERAB	O
,	O
MODAB	O
,	O
PLUSTO	O
,	O
</s>
<s>
The	O
LWB	O
and	O
UPB	O
operators	O
are	O
automatically	O
available	O
on	O
UNIONs	O
of	O
different	O
orders	O
(	O
and	O
MODEs	O
)	O
of	O
arrays	B-Data_Structure
.	O
</s>
<s>
PRIOrity(Quaternaries )	O
Algol68	B-Language
"	O
Worthy	O
characters	O
"	O
r0&r1+Algol68r0&r1+Algol68C	O
,	O
G	O
,	O
R+Algol68r0	O
Effectively	O
0	O
:=	O
,	O
IS	O
:=	O
:	O
,	O
ISNT	O
:/	O
=	O
:	O
:	O
~	O
=	O
:	O
,	O
AT	O
@	O
,	O
"	O
:	O
"	O
,	O
"	O
;	O
"	O
:	O
≠	O
:	O
:	O
¬	O
=	O
:	O
:=	O
:=	O
C	B-Language
,	O
=	O
:=	O
R	O
..	O
=	O
,	O
.	O
=	O
,	O
CT	O
,	O
::	O
,	O
CTAB	O
,	O
::	O
=	O
,	O
..	O
,	O
is	O
not	O
,	O
"	O
..	O
"	O
,	O
"	O
.	O
,	O
"	O
</s>
<s>
while	O
legal	O
,	O
will	O
probably	O
not	O
do	B-Language
what	O
might	O
be	O
expected	O
.	O
</s>
<s>
Most	O
of	O
Algol	B-Language
's	O
"	O
special	O
"	O
characters	O
( ⊂	O
,	O
≡	O
,	O
␣	O
,	O
×	O
,	O
÷	O
,	O
≤	O
,	O
≥	O
,	O
≠	O
,	O
¬	O
,	O
⊃	O
,	O
≡	O
,	O
∨	O
,	O
∧	O
,	O
→	O
,	O
↓	O
,	O
↑	O
,	O
⌊	O
,	O
⌈	O
,	O
⎩	O
,	O
⎧	O
,	O
⊥	O
,	O
⏨	O
,	O
¢	O
,	O
○	O
and	O
□	O
)	O
can	O
be	O
found	O
on	O
the	O
IBM	O
2741	O
keyboard	O
with	O
the	O
APL	O
"	O
golf-ball	O
"	O
print	O
head	O
inserted	O
;	O
these	O
became	O
available	O
in	O
the	O
mid-1960s	O
while	O
ALGOL	B-Language
68	I-Language
was	O
being	O
drafted	O
.	O
</s>
<s>
Transput	O
is	O
the	O
term	O
used	O
to	O
refer	O
to	O
ALGOL	B-Language
68	I-Language
's	O
input	O
and	O
output	O
facilities	O
.	O
</s>
<s>
"	O
Formatted	O
transput	O
"	O
in	O
ALGOL	B-Language
68	I-Language
's	O
transput	O
has	O
its	O
own	O
syntax	O
and	O
patterns	O
(	O
functions	O
)	O
,	O
with	O
FORMATs	O
embedded	O
between	O
two	O
$	O
characters	O
.	O
</s>
<s>
ALGOL	B-Language
68	I-Language
supports	O
programming	O
of	O
parallel	B-Operating_System
processing	I-Operating_System
.	O
</s>
<s>
Using	O
the	O
keyword	O
PAR	O
,	O
a	O
collateral	O
clause	O
is	O
converted	O
to	O
a	O
parallel	B-Operating_System
clause	O
,	O
where	O
the	O
synchronisation	O
of	O
actions	O
is	O
controlled	O
using	O
semaphores	B-Operating_System
.	O
</s>
<s>
In	O
A68G	O
the	O
parallel	B-Operating_System
actions	O
are	O
mapped	O
to	O
threads	O
when	O
available	O
on	O
the	O
hosting	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
In	O
A68S	O
a	O
different	O
paradigm	O
of	O
parallel	B-Operating_System
processing	I-Operating_System
was	O
implemented	O
(	O
see	O
below	O
)	O
.	O
</s>
<s>
This	O
sample	O
program	O
implements	O
the	B-Algorithm
Sieve	I-Algorithm
of	I-Algorithm
Eratosthenes	I-Algorithm
to	O
find	O
all	O
the	O
prime	O
numbers	O
that	O
are	O
less	O
than	O
100	O
.	O
</s>
<s>
NIL	O
is	O
the	O
ALGOL	B-Language
68	I-Language
analogue	O
of	O
the	O
null	O
pointer	O
in	O
other	O
languages	O
.	O
</s>
<s>
The	O
notation	O
x	O
OF	O
y	O
accesses	O
a	O
member	O
x	O
of	O
a	O
STRUCT	B-Language
y	O
.	O
</s>
<s>
MODE	O
NODE	O
=	O
STRUCT	B-Language
(	O
INT	O
h	O
,	O
LIST	O
t	O
)	O
;	O
</s>
<s>
Cambridge	B-Device
CAP	I-Device
computer	I-Device
–	O
All	O
procedures	O
constituting	O
the	O
operating	B-General_Concept
system	I-General_Concept
were	O
written	O
in	O
ALGOL	B-General_Concept
68C	I-General_Concept
,	O
although	O
several	O
other	O
closely	O
associated	O
protected	O
procedures	O
,	O
such	O
as	O
a	O
paginator	O
,	O
are	O
written	O
in	O
BCPL	B-Language
.	O
</s>
<s>
Eldon	O
3	O
–	O
Developed	O
at	O
Leeds	O
University	O
for	O
the	O
ICL	B-Device
1900	I-Device
was	O
written	O
in	O
ALGOL	B-General_Concept
68-R	I-General_Concept
.	O
</s>
<s>
Flex	B-Device
machine	I-Device
–	O
The	O
hardware	O
was	O
custom	O
and	O
microprogrammable	O
,	O
with	O
an	O
operating	B-General_Concept
system	I-General_Concept
,	O
(	O
modular	O
)	O
compiler	B-Language
,	O
editor	O
,	O
garbage	O
collector	O
and	O
filing	O
system	O
all	O
written	O
in	O
ALGOL	B-General_Concept
68RS	I-General_Concept
.	O
</s>
<s>
The	O
command	O
shell	O
Curt	O
was	O
designed	O
to	O
access	O
typed	O
data	O
similar	O
to	O
Algol-68	B-Language
modes	O
.	O
</s>
<s>
VME	B-General_Concept
–	O
S3	B-Language
was	O
the	O
implementation	O
language	O
of	O
the	O
operating	B-General_Concept
system	I-General_Concept
VME	B-General_Concept
.	O
</s>
<s>
S3	B-Language
was	O
based	O
on	O
ALGOL	B-Language
68	I-Language
but	O
with	O
data	O
types	O
and	O
operators	O
aligned	O
to	O
those	O
offered	O
by	O
the	O
ICL	B-Device
2900	I-Device
Series	I-Device
.	O
</s>
<s>
Note	O
:	O
The	O
Soviet	O
Era	O
computers	O
Эльбрус-1	O
(	O
Elbrus-1	O
)	O
and	O
Эльбрус-2	O
were	O
created	O
using	O
high-level	O
language	O
Эль-76	O
(	O
AL-76	O
)	O
,	O
rather	O
than	O
the	O
traditional	O
assembly	O
.	O
</s>
<s>
Эль-76	O
resembles	O
Algol-68	B-Language
,	O
The	O
main	O
difference	O
is	O
the	O
dynamic	O
binding	O
types	O
in	O
Эль-76	O
supported	O
at	O
the	O
hardware	O
level	O
.	O
</s>
<s>
Both	O
ALGOL	B-General_Concept
68C	I-General_Concept
and	O
ALGOL	B-General_Concept
68-R	I-General_Concept
are	O
written	O
in	O
ALGOL	B-Language
68	I-Language
,	O
effectively	O
making	O
ALGOL	B-Language
68	I-Language
an	O
application	O
of	O
itself	O
.	O
</s>
<s>
ELLA	B-Language
–	O
a	O
hardware	O
description	O
language	O
and	O
support	O
toolset	O
.	O
</s>
<s>
NAG	O
Numerical	O
Libraries	O
–	O
a	O
software	B-Library
library	I-Library
of	O
numerical	B-General_Concept
analysis	I-General_Concept
routines	O
.	O
</s>
<s>
Supplied	O
in	O
ALGOL	B-Language
68	I-Language
during	O
the	O
1980s	O
.	O
</s>
<s>
A	O
feature	O
of	O
ALGOL	B-Language
68	I-Language
,	O
inherited	O
from	O
the	O
ALGOL	B-Language
tradition	O
,	O
is	O
its	O
different	O
representations	O
.	O
</s>
<s>
There	O
is	O
a	O
representation	O
language	O
used	O
to	O
describe	O
algorithms	O
in	O
printed	O
work	O
,	O
a	O
strict	O
language	O
(	O
rigorously	O
defined	O
in	O
the	O
Report	O
)	O
,	O
and	O
an	O
official	O
reference	O
language	O
intended	O
to	O
be	O
used	O
in	O
compiler	B-Language
input	O
.	O
</s>
<s>
ALGOL	B-Language
68	I-Language
's	O
reserved	O
words	O
are	O
effectively	O
in	O
a	O
different	O
namespace	O
from	O
identifiers	O
,	O
and	O
spaces	O
are	O
allowed	O
in	O
identifiers	O
,	O
so	O
this	O
next	O
fragment	O
is	O
legal	O
:	O
</s>
<s>
This	O
is	O
called	O
a	O
stropping	B-Application
regime	O
.	O
</s>
<s>
Of	O
these	O
,	O
POINT	O
and	O
UPPER	O
stropping	B-Application
are	O
quite	O
common	O
,	O
while	O
RES	O
stropping	B-Application
is	O
a	O
contradiction	O
to	O
the	O
specification	O
(	O
as	O
there	O
are	O
no	O
reserved	O
words	O
)	O
.	O
</s>
<s>
QUOTE	O
(	O
single	O
apostrophe	O
quoting	O
)	O
was	O
the	O
original	O
recommendation	O
,	O
while	O
matched	O
apostrophe	O
quoting	O
,	O
common	O
in	O
ALGOL	B-Language
60	I-Language
,	O
is	O
not	O
used	O
much	O
in	O
ALGOL	B-Language
68	I-Language
.	O
</s>
<s>
ALGOL	B-Language
68	I-Language
allows	O
for	O
every	O
natural	O
language	O
to	O
define	O
its	O
own	O
set	O
of	O
keywords	O
Algol-68	B-Language
.	O
</s>
<s>
MODE	O
DATE	O
=	O
STRUCT(INT day, STRING month, INT year )	O
;	O
</s>
<s>
In	O
English	O
Algol68	B-Language
's	O
case	O
statement	O
reads	O
CASE	O
~	O
IN	O
~	O
OUT	O
~	O
ESAC	O
,	O
in	O
Cyrillic	O
this	O
reads	O
выб	O
~	O
в	O
~	O
либо	O
~	O
быв	O
.	O
</s>
<s>
For	O
its	O
technical	O
intricacies	O
,	O
ALGOL	B-Language
68	I-Language
needs	O
a	O
cornucopia	O
of	O
methods	O
to	O
deny	O
the	O
existence	O
of	O
something	O
:	O
</s>
<s>
"	O
C	B-Language
–	O
an	O
undefined	O
value	O
always	O
syntactically	O
valid	O
,	O
</s>
<s>
ℵ	O
–	O
Used	O
in	O
the	O
standards	O
report	O
to	O
inhibit	O
introspection	B-Application
of	O
certain	O
types	O
.	O
</s>
<s>
c.f.	O
</s>
<s>
ALGOL	B-Language
68	I-Language
leaves	O
intentionally	O
undefined	O
what	O
happens	O
in	O
case	O
of	O
integer	B-Error_Name
overflow	I-Error_Name
,	O
the	O
integer	O
bit	O
representation	O
,	O
and	O
the	O
degree	O
of	O
numerical	O
accuracy	O
for	O
floating	O
point	O
.	O
</s>
<s>
In	O
contrast	O
,	O
the	O
language	O
Java	B-Language
has	O
been	O
criticized	O
for	O
over-specifying	O
the	O
latter	O
.	O
</s>
<s>
Examples	O
include	O
"	O
≮	O
"	O
and	O
"	O
≯	O
"	O
for	O
templates	O
,	O
the	O
OUTTYPE/INTYPE	O
for	O
crude	O
duck	B-Application
typing	I-Application
,	O
and	O
the	O
STRAIGHTOUT	O
and	O
STRAIGHTIN	O
operators	O
for	O
"	O
straightening	O
"	O
nested	O
arrays	B-Data_Structure
and	O
structures	O
.	O
</s>
<s>
c	B-Language
)	O
MODE	O
ℵ	O
SIMPLIN	O
=	O
UNION	O
( ≮REF	O
ℒ	O
INT≯	O
,	O
≮REF	O
ℒ	O
REAL≯	O
,	O
≮REF	O
ℒ	O
COMPL≯	O
,	O
REF	O
BOOL	O
,	O
</s>
<s>
A	O
Comparison	O
of	O
PL/1	B-Language
and	O
ALGOL	B-Language
68	I-Language
.	O
International	O
Symposium	O
on	O
Computers	O
and	O
Chinese	O
Input/Output	O
Systems	O
.	O
</s>
<s>
1976	O
–	O
Evaluation	O
of	O
ALGOL	B-Language
68	I-Language
,	O
JOVIAL	B-Language
J3B	O
,	O
Pascal	B-Application
,	O
Simula	B-Language
67	I-Language
,	O
and	O
TACPOL	B-Language
Versus	O
TINMAN	O
–	O
Requirements	O
for	O
a	O
Common	O
High	O
Order	O
Programming	O
Language	O
.	O
</s>
<s>
1976	O
–	O
Evaluation	O
of	O
ALGOL	B-Language
68	I-Language
,	O
JOVIAL	B-Language
J3B	O
,	O
PASCAL	B-Application
,	O
SIMULA	B-Language
67	I-Language
,	O
and	O
TACPOL	B-Language
Versus	O
[	O
Steelman	O
language	O
requirements|TINMAN ]	O
Requirements	O
for	O
a	O
Common	O
High	O
Order	O
Programming	O
Language	O
.	O
</s>
<s>
1977	O
–	O
–	O
Executive	O
Summary	O
–	O
Language	O
Evaluation	O
Coordinating	O
Committee	O
–	O
Evaluation	O
of	O
PL/I	B-Language
,	O
Pascal	B-Application
,	O
ALGOL	B-Language
68	I-Language
,	O
HAL/S	B-Language
,	O
PEARL	B-Language
,	O
SPL/I	B-Language
,	O
PDL/2	O
,	O
LTR	O
,	O
CS-4	B-Language
,	O
LIS	B-General_Concept
,	O
Euclid	B-Language
,	O
ECL	B-Language
,	O
Moral	O
,	O
RTL/2	B-Language
,	O
Fortran	B-Application
,	O
COBOL	B-Application
,	O
ALGOL	B-Language
60	I-Language
,	O
TACPOL	B-Language
,	O
CMS-2	B-Language
,	O
Simula	B-Language
67	I-Language
,	O
JOVIAL	B-Language
J3B	O
,	O
JOVIAL	B-Language
J73	I-Language
&	O
Coral	B-Language
66	I-Language
.	O
</s>
<s>
1980	O
–	O
–	O
Algol	B-Language
60	I-Language
,	O
FORTRAN	B-Application
,	O
Pascal	B-Application
and	O
Algol	B-Language
68	I-Language
.	O
</s>
<s>
1993	O
–	O
–	O
BLISS	B-Language
,	O
Pascal	B-Application
,	O
Algol	B-Language
68	I-Language
,	O
BCPL	B-Language
&	O
C	B-Language
–	O
Dennis	O
M	O
.	O
Ritchie	O
–	O
April	O
1993	O
.	O
</s>
<s>
2009	O
–	O
–	O
How	O
well	O
will	O
Google	O
's	O
Go	B-Application
stand	O
up	O
against	O
Brand	O
X	O
programming	O
language	O
?	O
</s>
<s>
As	O
defined	O
in	O
ALGOL	B-Language
68	I-Language
,	O
it	O
did	O
not	O
work	O
as	O
expected	O
,	O
for	O
example	O
in	O
the	O
code	O
:	O
</s>
<s>
then	O
the	O
compiler	B-Language
could	O
evaluate	O
the	O
arguments	O
in	O
whatever	O
order	O
it	O
felt	O
like	O
.	O
</s>
<s>
mode	O
parameters	O
:	O
for	O
implementation	O
of	O
limited	O
parametrical	O
polymorphism	B-Application
(	O
most	O
operations	O
on	O
data	O
structures	O
like	O
lists	O
,	O
trees	O
or	O
other	O
data	O
containers	O
can	O
be	O
specified	O
without	O
touching	O
the	O
pay	O
load	O
)	O
.	O
</s>
<s>
So	O
far	O
,	O
only	O
partial	O
parametrisation	O
has	O
been	O
implemented	O
,	O
in	O
Algol	B-Language
68	I-Language
Genie	O
.	O
</s>
<s>
Name	O
Year	O
Purpose	O
State	O
Description	O
Target	O
CPU	O
Licensing	O
Implementation	O
languageGeneralized	O
ALGOL	B-Language
1962	O
Scientific	O
NL	O
ALGOL	B-Language
for	O
generalised	O
grammars	O
ALGOL	B-Language
YY	O
1966	O
Draft	O
proposal	O
Intl	O
First	O
version	O
of	O
Algol	B-Language
68	I-Language
Specification	O
ACM	O
ALGOL	B-Language
68DR	O
1968	O
Draft	O
proposal	O
Intl	O
IFIP	B-Language
WG	I-Language
2.1	I-Language
Draft	O
Report	O
Specification	O
–	O
March	O
ACM	O
ALGOL	B-Language
68r0	O
1968	O
Standard	O
Intl	O
IFIP	B-Language
WG	I-Language
2.1	I-Language
Final	O
Report	O
Specification	O
–	O
August	O
ACM	O
ALGOL	B-Language
68-RR	O
1970	O
Military	O
UK	O
ICL	B-Device
1900	I-Device
ALGOL	B-Language
60EPOS	O
ALGOLE	O
1971	O
Scientific	O
ALGOL	B-Language
68RSRS	O
1972	O
Military	O
UK	O
Portable	O
compiler	B-Language
system	O
ICL	O
2900/Series	O
39	O
,	O
Multics	B-Application
,	O
VMS	O
&	O
Crown	O
Copyright	O
ALGOL	B-Language
68RSAlgol	O
68	O
with	O
areas	O
1972	O
Experimental	O
&	O
other	O
UK	O
Addition	O
of	O
areas	O
to	O
Algol	B-Language
68	I-Language
Mini	O
ALGOL	B-Language
68	I-Language
1973	O
Research	O
NL	O
"	O
An	O
interpreter	O
for	O
simple	O
Algol	B-Language
68	I-Language
Programs	O
"	O
Portable	O
interpreter	O
Mathematisch	O
Centrum	O
ALGOL	B-Language
60OREGANO	O
1973	O
Research	O
US	O
"	O
The	O
importance	O
of	O
implementation	O
models.	O
"	O
</s>
<s>
UCLA	O
ALGOL	B-Language
68CC	O
1975	O
Scientific	O
UK	O
Cambridge	O
Algol	B-Language
68	I-Language
ICL	O
,	O
IBM	O
360	O
,	O
PDP	O
10	O
&	O
Unix	B-Application
,	O
Telefunken	O
,	O
Tesla	O
&	O
Z80	B-General_Concept
(	O
1980	O
)	O
Cambridge	O
ALGOL	B-Language
68CALGOL	O
68	O
Revised	O
Reportr1	O
1975	O
Standard	O
Intl	O
IFIP	B-Language
WG	I-Language
2.1	I-Language
Revised	O
Report	O
Specification	O
ACM	O
Algol	B-Language
HH	O
1975	O
Experimental	O
&	O
other	O
UK	O
Proposed	O
extensions	O
to	O
the	O
mode	O
system	O
of	O
Algol	B-Language
68	I-Language
Specification	O
ALGOL	B-Language
WOdra	O
Algol	B-Language
68	I-Language
1976	O
practical	O
uses	O
USSR/Poland	O
Odra	B-Device
1204/IL	O
Soviet	O
ALGOL	B-Language
60Oklahoma	O
ALGOL	B-Language
68	I-Language
1976	O
programming	O
instruction	O
USA	O
Oklahoma	O
State	O
University	O
implementationhttp://htportal.acm.org/ft_gateway.cfm	O
?	O
id	O
=	O
803425&type	O
=	O
pdf	O
IBM	B-Device
1130	I-Device
and	O
System/370/158	O
Unknown	O
ANSI	O
Fortran	B-Application
66.Berlin	O
ALGOL	B-Language
68	I-Language
1977	O
Research	O
DE	O
"	O
The	O
Berlin	O
ALGOL	B-Language
68	I-Language
implementation	O
"	O
&	O
An	O
abstract	O
ALGOL	B-Language
68	I-Language
machine	O
and	O
its	O
application	O
in	O
a	O
machine	O
independent	O
compiler	B-Language
–	O
Springer	O
.	O
</s>
<s>
An	O
Abstract	O
ALGOL	B-Language
68	I-Language
Machine	O
–	O
machine	O
independent	O
Compiler	B-Language
Technical	O
University	O
of	O
Berlin	O
CDL	O
2FLACCF	O
1977	O
Multi-purpose	O
CA	O
Revised	O
Report	O
complete	O
implementation	O
with	O
debug	O
features	O
System/370	B-Device
lease	O
,	O
Chion	O
Corporation	O
AssemblerALGOL	O
68-RTRT	O
1979	O
Scientific	O
UK	O
Parallel	B-Operating_System
ALGOL	B-General_Concept
68-R	I-General_Concept
RS	O
Algolrs	O
1979	O
Scientific	O
UK	O
ALGOL	B-Language
68+	O
1980	O
Scientific	O
NL	O
Proposed	O
superlanguage	O
of	O
ALGOL	B-Language
68	I-Language
M-220	O
ALGOL	B-Language
68	I-Language
USSR	O
M-220	O
Soviet	O
EPSILONLeningrad	O
ALGOL	B-Language
68L	O
1980	O
Telecommunications	O
USSR	O
Full	O
language	O
+	O
modules	O
IBM	O
,	O
DEC	O
,	O
CAMCOH	O
,	O
PS	O
1001	O
&	O
PC	O
Soviet	O
Interactive	O
ALGOL	B-Language
68I	O
1983	O
UK	O
Incremental	B-Application
compilation	I-Application
PC	O
Noncommercial	O
shareware	B-License
ALGOL	B-Language
68SS	O
1985	O
Scientific	O
Intl	O
Sun	O
version	O
of	O
ALGOL	B-Language
68	I-Language
Sun-3	B-Device
,	O
Sun	B-Architecture
SPARC	I-Architecture
(	O
under	O
SunOS	B-Operating_System
4.1	I-Operating_System
&	O
Solaris	B-Application
2	O
)	O
,	O
Atari	B-Device
ST	I-Device
(	O
under	O
GEMDOS	B-Device
)	O
,	O
Acorn	B-Device
Archimedes	I-Device
(	O
under	O
RISC	B-Operating_System
OS	I-Operating_System
)	O
,	O
VAX-11	O
under	O
Ultrix-32	B-Operating_System
Algol68toCOpen	O
source	O
Algol	B-Language
68	I-Language
implementations	O
–	O
Browse	O
Files	O
at	O
.	O
</s>
<s>
The	O
S3	B-Language
language	I-Language
that	O
was	O
used	O
to	O
write	O
the	O
ICL	B-General_Concept
VME	I-General_Concept
operating	B-General_Concept
system	I-General_Concept
and	O
much	O
other	O
system	O
software	O
on	O
the	O
ICL	B-Device
2900	I-Device
Series	I-Device
was	O
a	O
direct	O
derivative	O
of	O
Algol	B-Language
68	I-Language
.	O
</s>
<s>
ALGOL	O
68R(R )	O
from	O
RRE	O
was	O
the	O
first	O
ALGOL	B-Language
68	I-Language
subset	O
implementation	O
,	O
running	O
on	O
the	O
ICL	B-Device
1900	I-Device
.	O
</s>
<s>
Based	O
on	O
the	O
original	O
language	O
,	O
the	O
main	O
subset	O
restrictions	O
were	O
definition	O
before	O
use	O
and	O
no	O
parallel	B-Operating_System
processing	I-Operating_System
.	O
</s>
<s>
This	O
compiler	B-Language
was	O
popular	O
in	O
UK	O
universities	O
in	O
the	O
1970s	O
,	O
where	O
many	O
computer	B-General_Concept
science	I-General_Concept
students	O
learnt	O
ALGOL	B-Language
68	I-Language
as	O
their	O
first	O
programming	O
language	O
;	O
the	O
compiler	B-Language
was	O
renowned	O
for	O
good	O
error	O
messages	O
.	O
</s>
<s>
ALGOL	O
68RS(RS )	O
from	O
RSRE	O
was	O
a	O
portable	O
compiler	B-Language
system	O
written	O
in	O
ALGOL	B-General_Concept
68RS	I-General_Concept
(	O
bootstrapped	O
from	O
ALGOL	B-General_Concept
68R	I-General_Concept
)	O
,	O
and	O
implemented	O
on	O
a	O
variety	O
of	O
systems	O
including	O
the	O
ICL	O
2900/Series	O
39	O
,	O
Multics	B-Application
and	O
DEC	B-Device
VAX/VMS	I-Device
.	O
</s>
<s>
The	O
language	O
was	O
based	O
on	O
the	O
Revised	O
Report	O
,	O
but	O
with	O
similar	O
subset	O
restrictions	O
to	O
ALGOL	B-General_Concept
68R	I-General_Concept
.	O
</s>
<s>
This	O
compiler	B-Language
survives	O
in	O
the	O
form	O
of	O
an	O
Algol68-to-C	O
compiler	B-Language
.	O
</s>
<s>
In	O
ALGOL	O
68S(S )	O
from	O
Carnegie	O
Mellon	O
University	O
the	O
power	O
of	O
parallel	B-Operating_System
processing	I-Operating_System
was	O
improved	O
by	O
adding	O
an	O
orthogonal	O
extension	O
,	O
eventing	O
.	O
</s>
<s>
Any	O
variable	O
declaration	O
containing	O
keyword	O
EVENT	O
made	O
assignments	O
to	O
this	O
variable	O
eligible	O
for	O
parallel	B-Operating_System
evaluation	O
,	O
i.e.	O
</s>
<s>
the	O
right	O
hand	O
side	O
was	O
made	O
into	O
a	O
procedure	O
which	O
was	O
moved	O
to	O
one	O
of	O
the	O
processors	O
of	O
the	O
C.mmp	B-Operating_System
multiprocessor	O
system	O
.	O
</s>
<s>
Cambridge	O
ALGOL	O
68C(C )	O
was	O
a	O
portable	O
compiler	B-Language
that	O
implemented	O
a	O
subset	O
of	O
ALGOL	B-Language
68	I-Language
,	O
restricting	O
operator	O
definitions	O
and	O
omitting	O
garbage	O
collection	O
,	O
flexible	O
rows	O
and	O
formatted	O
transput	O
.	O
</s>
<s>
Algol	B-Language
68	I-Language
Genie(G )	O
by	O
M	O
.	O
van	O
der	O
Veer	O
is	O
an	O
ALGOL	B-Language
68	I-Language
implementation	O
for	O
today	O
's	O
computers	O
and	O
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
While	O
this	O
option	O
is	O
in	O
force	O
,	O
the	O
compiler	B-Language
prints	O
a	O
message	O
for	O
each	O
construct	O
that	O
it	O
recognizes	O
as	O
violating	O
some	O
portability	O
constraint.	O
"	O
</s>
<s>
The	O
scheme	O
of	O
type	O
composition	O
adopted	O
by	O
C	B-Language
owes	O
considerable	O
debt	O
to	O
Algol	B-Language
68	I-Language
,	O
although	O
it	O
did	O
not	O
,	O
perhaps	O
,	O
emerge	O
in	O
a	O
form	O
that	O
Algol	B-Language
's	O
adherents	O
would	O
approve	O
of	O
.	O
</s>
<s>
The	O
central	O
notion	O
I	O
captured	O
from	O
Algol	B-Language
was	O
a	O
type	O
structure	O
based	O
on	O
atomic	O
types	O
(	O
including	O
structures	O
)	O
,	O
composed	O
into	O
arrays	B-Data_Structure
,	O
pointers	O
(	O
references	O
)	O
,	O
and	O
functions	O
(	O
procedures	O
)	O
.	O
</s>
<s>
Algol	B-Language
68	I-Language
's	O
concept	O
of	O
unions	O
and	O
casts	O
also	O
had	O
an	O
influence	O
that	O
appeared	O
later	O
.	O
</s>
<s>
...	O
C	B-Language
does	O
not	O
descend	O
from	O
Algol	B-Language
68	I-Language
is	O
true	O
,	O
yet	O
there	O
was	O
influence	O
,	O
much	O
of	O
it	O
so	O
subtle	O
that	O
it	O
is	O
hard	O
to	O
recover	O
even	O
when	O
I	O
think	O
hard	O
.	O
</s>
<s>
In	O
particular	O
,	O
the	O
union	O
type	O
(	O
a	O
late	O
addition	O
to	O
C	B-Language
)	O
does	O
owe	O
to	O
A68	O
,	O
not	O
in	O
any	O
details	O
,	O
but	O
in	O
the	O
idea	O
of	O
having	O
such	O
a	O
type	O
at	O
all	O
.	O
</s>
<s>
 [ ... ] 	O
The	O
best	O
we	O
could	O
do	B-Language
was	O
to	O
send	O
with	O
it	O
a	O
minority	O
report	O
,	O
stating	O
our	O
considered	O
view	O
that	O
,	O
"	O
...	O
as	O
a	O
tool	O
for	O
the	O
reliable	O
creation	O
of	O
sophisticated	O
programs	O
,	O
the	O
language	O
was	O
a	O
failure.	O
"	O
</s>
