From: Dave Thomas <dave@...>
Date: 2008-05-01T12:26:47+09:00
Subject: lambda, ->, haskell, and so on

This is one of those e-mails that I know from the start to be futile,  
but...

For a while now, the

      -> (params) { block }

syntax in Ruby 1.9 has bothered me, but I've never been sure why.  
Today, while playing with pure, it struck me. The '->' sequence is in  
an unexpected place. Having played with some functional languages, I'm  
used to lambdas being written

   \ params -> block

That is, the lambda is introduced with a \ (because, presumably, it  
looks a bit like ��). The -> sequence separates the parameters from the  
block. This had become ingrained into be, in the same way that the  
equals sign in an assignment

   a = expression

goes between the lvalue and the rvalue.

So, when I come to Ruby 1.9, suddenly there's some dissonance between  
what I was used to and what I now have to type. The -> comes before  
the parameters, not after. It's as if I had to write assignments

   = a expression

So, here's the futile part... :)

Is it too late for Ruby 1.9 to support lambdas that look like

   \ p1, p1 -> { block }

I honestly feel this would be more natural, and more in line with the  
prevailing idioms. I suspect it's parsable if you make the simplifying  
assumption that line continuations must only have whitespace after them.



Dave