What it needs is a `-e` flag:

    ruby -e 'puts 5 + 7'

Can you please elaborate on how that would help?

Is it just for familiarity/similarity? I kinda see the 'e' from ruby -e going after the go to form goe. goe -e would be just redundant, wouldn't it?

Perl, Ruby, Python, and many others have a succinct "evaluate this string" command-line flag. It's so commonplace it's to be expected.