Also check out CanSpec.scala to get an idea of how Cans can be used.
--j
On Wed, Oct 15, 2008 at 9:33 AM, David Pollak <[EMAIL PROTECTED]> wrote:
> Charles,
>
> A Can is a container... it can contain a thing or be empty.
>
> You can transform the contents of a Can from one thing to another using
> map(). map() on Can, Option, List is exactly the same as map() on Array in
> Ruby:
> irb(main):004:0> [1,2,3].map{|v| v.to_s + " Cats"}
> => ["1 Cats", "2 Cats", "3 Cats"]
>
> This is just like in Scala:
> scala> List(1,2,3).map(v => v.toString + " Cats")
> res0: List[java.lang.String] = List(1 Cats, 2 Cats, 3 Cats)
>
> In Ruby, when you access the first element of an Array that has no
> elements, you get 'nil' back. In Scala, you get an exception. This allows
> you to tell the difference between [nil][0] and [][0] which are the same in
> Ruby.
>
> The most syntactically pleasing way of extracting things from List, Can,
> Option in Scala is the "for" comprehension:
>
> scala> for (a <- Some(3);
> | b <- Some(4)) yield a * b
> res1: Option[Int] = Some(12)
>
>
> Does that help?
>
> Thanks,
>
> David
>
>
>
>
> Charles F. Munat wrote:
>
> Thanks. I have read everything I could find on this but I think I'm just
> a bit dense about it. Probably, it's just unfamiliarity with the syntax
> of Scala as a whole and functional programming in general (or maybe I'm
> just stupid). Hopefully, at some point the light bulb will come on and
> this will seem easy. I'll read the blog post.
>
> Chas.
>
> David Pollak wrote:
>
>
> Please also
> see:http://blog.lostlake.org/index.php?/archives/50-The-Scala-Option-class-and-how-lift-uses-it.html
>
> Can[T] is just like Option[T]
>
> Marius wrote:
>
>
> to get stuff out of a can you can do:
>
> 1. Pattern matching
>
> having c a Can[String]
>
> c match {
> case Full(value) => //do something with the value
> case _ =>
> }
>
> 2. call open_!(if you're sure your can is not empty) or openOr
>
> Br's,
> Marius
>
> On Oct 15, 3:22 am, "Charles F. Munat" <[EMAIL PROTECTED]> <[EMAIL
> PROTECTED]> wrote:
>
>
>
> I must be very dense, but these cans are kicking my butt (kicking my
> can?). No matter what I do, I seem to end up with everything back in the
> can! I just... want... to get... the goodies... OUT!
>
> An example:
>
> How do I extract the URI of the current page from S.request?
>
> I am currently doing something immensely stupid and wrong like this:
>
> S.request.toList.head.location.toList.head.createDefaultLink.toList.head.text
>
> I *know* this is way wrong, but I'm not clever enough, apparently, to
> figure out the puzzle, despite reading through the Can code repeatedly.
> I figure the above works only because what I'm looking for is there,
> which sort of defeats the purpose of the cans...
>
> Can anyone help? This is driving me insane.
>
> Chas.
>
>
>
>
>
> >
>
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