[patrec]

It's been a while since I last wrote CL but I think your program can produce any counts between zero and the correct one – you need to use eql instead of eq if you want this to work in standard common lisp.

[tazjin]

Ah, you're right of course - fixed. Though that still won't make this portable, as I'm using an SBCL-specific way of accessing argv.

[gmfawcett]

`unix-opts` is in available in quicklisp -- it's small, and has a portable `argv` wrapper function.

[tazjin]

Thanks for the tip, added that: https://git.tazj.in/commit/?id=10e2e56b67b41eb6315fdc4cc1bc1...