Re: Possible Lua enhancements 2: Piping

[Mark Hamburg <mark@...>]

On Dec 17, 2008, at 2:39 PM, Ralph Hempel wrote:

> Mark Hamburg wrote:
> > The following ideas started with studying LINQ, but LINQ is pretty  
> > clearly just a piping model for data together with some useful  
> > syntax in C# and VB and ways to delay evaluation long enough to  
> > allow for translation into SQL or other mechanisms. I'm not going  
> > to address how to get to those latter enhancements but pipes are  
> > good as any Unix programmer will tell you and as Diego Nehab  
> > demonstrated in LTN 12 (http://lua-users.org/wiki/FiltersSourcesAndSinks 
> > ). So, here are two proposals for how to add pipes to Lua's syntax:
>
> Is this significantly different from the coroutine example in
> the PiL book  <http://www.lua.org/pil/9.2.html> that goes
> something like:
>
> consumer( filter ( producer() ) )
>
> Don't get me wrong, I like pipes, I'm just not seeing how
> the piping you're proposing is anything more than syntactic
> sugar for the above code...

It is just syntactic sugar. The point is that without the sugar, the  
pipe idiom becomes fairly difficult to follow fairly quickly. That's  
also why I don't particularly like the Haskell inspired approach (my  
option 2) which would basically turn the above into:

	consumer $ filter $ producer()

On the other hand, I think there is clarity to be gained from:

	producer() >> filter >> consumer

You can read the code left-to-right instead of inside-out and  
understand what it does.

Mark