User defined pipe and redirection operators: Difference between revisions
User defined pipe and redirection operators (view source)
Revision as of 05:30, 14 March 2021
, 3 years agojulia example
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<lang>Pioneer: * Adriaan van Wijngaarden - Dutch pioneer; ARRA, ALGOL</lang>
=={{header|Julia}}==
Uses Julia's Channels as asynchronous pipes. Note that the $( .. ) Unix command, which gathers stdin output into a single variable, is not used. Instead, a common output channel for various tasks is used to gather output.
<lang julia>const LISTDATA = """
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
"""
datafilename = "List_of_computer_scientists.lst"
stat(datafilename).size == 0 && (fd = open(datafilename, "a"); write(fd, LISTDATA); close(fd))
channelstream() = Channel{String}(rand(200:300))
closewhenempty(c) = @async begin while !isempty(c) sleep(rand()) end; close(c); end
function head(filename, numlines, chan=channelstream())
fd = open(filename)
buffer = String[]
while !eof(fd)
push!(buffer, readline(fd, keep=true))
length(buffer) == numlines && break
end
close(fd)
@async begin
for line in buffer
put!(chan, line)
end
closewhenempty(chan)
end
return chan
end
function cat(filename::AbstractString, chan=channelstream())
@async begin
fd = open(filename)
while !eof(fd)
put!(chan, readline(fd, keep=true))
end
close(fd)
closewhenempty(chan)
end
return chan
end
function grep(inchan::Channel, target)
outchan = channelstream()
@async begin
try
while isopen(inchan)
line = take!(inchan)
if occursin(target, line)
put!(outchan, line)
end
end
catch;
end
closewhenempty(outchan)
end
return outchan
end
grep(target) = (chan) -> grep(chan, target)
function tee(inchan::Channel, filename, outchan=channelstream())
fd = open(filename, "w")
@async begin
while isopen(inchan)
try
line = take!(inchan)
write(fd, line)
put!(outchan, line)
catch;
break
end
end
close(fd)
closewhenempty(outchan)
end
return outchan
end
tee(filename, outchan=channelstream()) = (inchan) -> tee(inchan, filename, outchan)
function tail(filename, numlines, chan=channelstream())
fd = open(filename)
buffer = String[]
while !eof(fd)
push!(buffer, readline(fd, keep=true))
length(buffer) > numlines && popfirst!(buffer)
end
@async begin
for line in buffer
put!(chan, line)
end
closewhenempty(chan)
end
return chan
end
function Sort(inchan)
outchan = channelstream()
buffer = String[]
try
while isopen(inchan)
push!(buffer, take!(inchan))
end
catch;
end
@async begin
for line in sort!(buffer)
put!(outchan, line)
end
closewhenempty(outchan)
end
return outchan
end
Sort() = (chan) -> Sort(chan)
function uniq(inchan)
outchan = channelstream()
alreadyseen = Set{String}()
@async begin
while isopen(inchan)
try
line = take!(inchan)
if !(line in alreadyseen)
push!(alreadyseen, line)
put!(outchan, line)
end
catch;
break
end
end
closewhenempty(outchan)
end
return outchan
end
uniq() = (chan) -> uniq(chan)
function lines(chan)
io = IOBuffer()
try
while isopen(chan)
print(io, take!(chan))
end
catch;
end
flush(io)
end
function print_lines(chan)
@async begin
while isopen(chan)
line = take!(chan)
print(line)
end
end
end
print_lines() = (chan) -> print_lines(chan)
const commonoutchan = channelstream()
head("List_of_computer_scientists.lst", 4, commonoutchan)
cat("List_of_computer_scientists.lst", commonoutchan)
cat("List_of_computer_scientists.lst") |> grep("ALGOL") |> tee("Algol_pioneers.lst", commonoutchan)
tail("List_of_computer_scientists.lst", 4, commonoutchan)
Sort(commonoutchan) |> uniq() |> tee("the_important_scientists.lst") |>
grep("aa") |> print_lines()
</lang>{{out}}
<pre>
Adriaan van Wijngaarden Dutch pioneer; ARRA, ALGOL
</pre>
=={{header|Perl}}==
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