reverse-complement Matz's Ruby program

# The Computer Language Benchmarks Game
# https://salsa.debian.org/benchmarksgame-team/benchmarksgame/
#
# Contributed by Aaron Tavistock

def process_segment(segment)
  (header, *body, tail) = segment.split("\n")

  # This is an ugly way to handle the first row, but returning nil causes the fork to implode
  return '' if !tail
  body << tail if tail != '>'

  sequence = body.join
  sequence.reverse!
  sequence.tr!(
    'wsatugcyrkmbdhvnATUGCYRKMBDHVN',
    'WSTAACGRYMKVHDBNTAACGRYMKVHDBN'
  )

  results = [">#{header}"]

  idx = 0
  length = sequence.length
  while idx < length
    results << sequence[idx,60]
    idx += 60
  end

  results.join("\n")
end

def forking_worker(segment)
  reader, writer = IO.pipe

  pid = Process.fork do
    begin
      reader.close
      results = process_segment(segment)
      Marshal.dump(results, writer) if results
    ensure
      writer.close
    end
  end

  writer.close
  begin
    results = Marshal.load(reader)
  ensure
    reader.close
  end
  Process.waitpid(pid)

  results
end

threads = []
$stdin.each_line('>') do |segment|
  threads << Thread.new do
      Thread.current[:output] = forking_worker(segment)
  end
end
threads.each(&:join)
threads.each do |thread|
  if !thread[:output].empty?  # Artifact of non-empty results from forking worker
    puts thread[:output]
  end
end
    

NOTES:
64-bit Ubuntu quad core
ruby 1.8.7 
(2014-01-28
patchlevel 376)
[x86_64-linux]



Thu, 09 Feb 2023 16:19:34 GMT

COMMAND LINE:
/usr/share/rvm/rubies/ruby-1.8.7-head/bin/ruby  revcomp.mri 0 < revcomp-input250000.txt

PROGRAM FAILED 


PROGRAM OUTPUT:

revcomp.mri:7: syntax error
  (header, *body, tail) = segment.split("\n")
                 ^