Thoughts on this?

    every [key, value] from arr {
      console.log(key, value);
    }

    every {key, value} from obj {
      console.log(key, value);
    }

    every [key] from arr {
      console.log(key);
    }

    every {_, value} from obj {
      console.log(value);
    }

Looks a bit cramped to me but I get the impression that array comprehension is one of the major reasons that people use Coffeescript, so perhaps it's not too much trouble?

There's also the issue with some fonts making it hard to differentiate between { and [ but it's an idea that might be worth to think about at least.