It meshes pretty well as is. If only I could get rid of the strings and redundant arguments.

  mymap = pattern {
    '_, []' : -> []
    'f, [x, xs...]' : (f, x, xs) -> 
      [f x].concat mymap(f, xs)
  }

It shares a lot of the same splat/rest/destructuring syntax.

Check out LiveScript's implicit switch syntax:

http://gkz.github.com/LiveScript/#switch

That's along similar lines, but more like guards in Haskell: http://en.wikibooks.org/wiki/Haskell/Control_structures

Last I heard, jashkenas was not a fan of adding such.

"... [P]attern matching inspired by static languages is a particularly poor fit for JavaScript (and by extension CoffeeScript), because types are extremely weak in JS." -jashkenas [1]

"[... P]attern matching is not nearly as useful in a language without rich types [...]" - jashkenas [2]

I'm on that reddit thread, respectfully disagreeing with him.

[1]: https://github.com/jashkenas/coffee-script/issues/1419#issue...

[2]: http://www.reddit.com/r/programming/comments/er0qj/coffeescr...