Primes utility

This program can generate primes, check numbers for prime-ness, or filter a list of numbers, passing only primes through. All input is on stdin.

Try it

$ ghc -O2 -dynamic primes
$ ./primes 20

Usage

Usage: primes [--check | [--stdin] [NUM_PRIMES]]

  -h, --help  print this message and exit
  --check     check all numbers given on stdin for primeness
  --stdin     reads numbers from stdin; copies primes to stdout
  NUM_PRIMES  only print the first NUM_PRIMES primes;
              if not given, output is potentially unbounded

If --check is given, the exit code 0 indicates all numbers were
prime; 1 indicates that at least one non-prime was passed in.