Note:
- These "pipes" can be any type (including tagged unions), in essence you have "strong typed" pipes (compile time checked) ... Perfect for a message passing system.
- The shell "&" can also be implemented. Happily the "&" is trivial when implemented with Algol68's parallel clause...
Hope you enjoy this "space-aged" code (a.k.a. 1960s code)... :-)
File: Iterator_pipe_operators.a68
MODE
PAGEIN = PAGE,
PAGEAPPEND = REF PAGE,
PAGEOUT = REF PAGE;
MODE
MOID = VOID,
YIELDLINE = PROC(LINE)VOID,
GENLINE = PROC(YIELDLINE)VOID,
FILTER = PROC(GENLINE)GENLINE, # the classic shell filter #
MANYTOONE = PROC([]GENLINE)GENLINE; # eg cat, as in con[cat]enate #
PRIO =: = 5, << = 5, >> = 5;
OP < = (FILTER filter, PAGEIN page)GENLINE: filter(READ page),
< = (MANYTOONE cmd, PAGEIN page)GENLINE: cmd(READ page),
<< = (FILTER filter, PAGEIN page)GENLINE: filter(READ page),
> = (GENLINE gen, PAGEOUT page)VOID: gen(WRITE page),
>> = (GENLINE gen, PAGEAPPEND page)VOID: gen(APPEND page),
=: = (GENLINE gen, FILTER filter)GENLINE: filter(gen),
=: = (GENLINE gen, MANYTOONE cmd)GENLINE: cmd(gen);
File: Iterator_pipe_utilities.a68
# Sample ''utilities'' PROCedure declarations #
PROC cat = ([]GENLINE argv)GENLINE:~;
PROC tee = ([]YIELDLINE args filter)FILTER:~;
PROC grep = (STRING pattern, []GENLINE argv)GENLINE:~;
PROC uniq = (GENLINE arg)GENLINE:~;
PROC sort = (GENLINE arg)GENLINE:~;
PROC head = (INT n, []GENLINE args)GENLINE:~;
PROC tail = (INT n, []GENLINE args)GENLINE:~;
File: Iterator_pipe_page.a68
# Sample ''pipe I/O'' OPerator declarations #
OP READ = (PAGEIN page)GENLINE:~;
OP WRITE = (PAGEOUT page)YIELDLINE: ~;
OP APPEND = (PAGEAPPEND page)YIELDLINE:~;
File: test_Iterator_pipe_page.a68
#!/usr/local/bin/a68g --script #
# First define what kind of record (aka LINE) we are piping and filtering #
FORMAT line fmt = $xg$;
MODE
LINE = STRING,
PAGE = FLEX[0]LINE,
BOOK = FLEX[0]PAGE;
PR READ "Iterator_pipe_page.a68" PR
PR READ "Iterator_pipe_operators.a68" PR
PR READ "Iterator_pipe_utilities.a68" PR
PAGE list of computer scientists = (
"Wil van der Aalst - business process management, process mining, Petri nets",
"Hal Abelson - intersection of computing and teaching",
"Serge Abiteboul - database theory",
"Samson Abramsky - game semantics",
"Leonard Adleman - RSA, DNA computing",
"Manindra Agrawal - polynomial-time primality testing",
"Luis von Ahn - human-based computation",
"Alfred Aho - compilers book, the 'a' in AWK",
"Stephen R. Bourne - Bourne shell, portable ALGOL 68C compiler",
"Kees Koster - ALGOL 68",
"Lambert Meertens - ALGOL 68, ABC (programming language)",
"Peter Naur - BNF, ALGOL 60",
"Guido van Rossum - Python (programming language)",
"Adriaan van Wijngaarden - Dutch pioneer; ARRA, ALGOL",
"Dennis E. Wisnosky - Integrated Computer-Aided Manufacturing (ICAM), IDEF",
"Stephen Wolfram - Mathematica",
"William Wulf - compilers",
"Edward Yourdon - Structured Systems Analysis and Design Method",
"Lotfi Zadeh - fuzzy logic",
"Arif Zaman - Pseudo-random number generator",
"Albert Zomaya - Australian pioneer of scheduling in parallel and distributed systems",
"Konrad Zuse - German pioneer of hardware and software"
);
PAGE algol pioneers list, the scientists list;
PAGE aa;
# Now do a bit of plumbing: #
cat((
head(4, ) < list of computer scientists,
cat(READ list of computer scientists) =: grep("ALGOL", ) =: tee(WRITE algol pioneers list),
tail(4, READ list of computer scientists)
)) =: sort =: uniq =: tee(WRITE the scientists list) =: grep("aa", ) >> aa;
# Finally check the result: #
printf((
$"Pioneer: "$, line fmt, aa, $l$,
$"Number of Algol pioneers: "g(-0)$, UPB algol pioneers list, $l$,
$"Number of scientists: "g(-0)$, UPB the scientists list, $l$
))
Output:
Pioneer: Adriaan van Wijngaarden - Dutch pioneer; ARRA, ALGOL
Number of Algol pioneers: 6
Number of scientists: 15
