arrow function syntax simplified

[Brendan Eich]

Allen Wirfs-Brock wrote:
> We don't need thin arrow and we really don't need the confusion it 
> would create.

The case for thin-arrow is body block. Instead rejecting -> and 
approving do-expressions results in something a bit overlong (=>do) that 
has TCP. And I think it's plausible that this will lead to completion 
value leaks, wrong-returns, etc. as Kevin suggests.

/be