> Ruby: a && b # `and` is available but is generally not recommended due to operator precedence

They're low priority in both languages. I use and see others using `and` and `or` all the time. In 15 years I can't say I've blown my foot off yet.

> Ruby: a = b ? c : d

If I'm really wanting a oneliner I'll tend to write

    a = if b then c else d end

You can of course spread it across a few lines:

    a = if b
      c
    else
      d
    end

More typically it's constructs like:

    a ||= b
    a = b if c
    a = b unless c

> Ruby: "abc" =~ /[a-z]{3}/

    /[a-z]{3}/.match("abc")

If you prefer.