From: Michael Hollins <mick@...>
Date: 2007-05-28T23:40:18+09:00
Subject: Re: Perspectives for Ruby 2.0

arcadiorubiogarcia@gmail.com wrote:
> On May 27, 12:31 pm, Michael Hollins <m...@hollins.id.au> wrote:
>> arcadiorubiogar...@gmail.com wrote:
>>
>>> 1. Are there any plans to introduce function currying? It's a very
>>> useful feature for function expressions, and it won't be very
>>> difficult to add. In fact, far I've seen a few implementations of it
>>> out there. They seem to be more or less ok, but it would be great to
>>> have it on the standard distribution.
>> what would you want beyond the following?
>>
>> http://moonbase.rydia.net/mental/blog/programming/currying-in-ruby
> 
> Well I would want something more implicit, like in Groovy for
> instance:
> http://www.ibm.com/developerworks/java/library/j-pg08235/index.html
> 
> 

So, just so I understand, take the following example:

   def multiply(a,b)
     a * b
   end

   triple = lambda { |a| multiply(a,3) }

   puts triple.call(10)

I believe you are saying that you'd like the last line to be:

   puts triple(10)

Is that right? If so, then I agree that would be nice. I'm guessing that it's difficult to achieve 
in ruby due to the fact that functions can be called without the parentheses. So, for example if I 
defined the following uninteresting lambda:

   six = lambda { multiply(2,3) }

then the following would be ambiguous:

   puts six

Am I trying to invoke the lambda, or am I trying to print the value of the object? To resolve the 
ambiguity I cannot invoke a lambda with the above syntax. Instead I need to do:

   puts six.call()

I'd like to hear from the experts if that is the reason or whether there is something more 
fundamental. I'm still learning ruby (and liking it BTW), so others will likely have a clearer 
perspective.

cheers,
mick