Block lambda is cool, its syntax isn't

[Thaddee Tyl]

I have heard many fellow programmers say that, while block lambdas
would be welcome, Ruby's |a, b| syntax is ugly.
I thought I was the only one feeling this way, but since I am not, I
would like to ask why the parentheses cannot be used there.

    { (a, b) a + b }

cannot conflict with any existing program; at least I don't see how it can.

This is a reaction to the following tweet:
https://twitter.com/#!/tabatkins/status/156813490785492992