A little background on implicits, maybe it'll help you.
A particular expression will only ever have one implicit conversion
applied -- the compiler will not attempt to chain together implicit
conversions (as I believe that's an NP problem)
So, the arguments to bind(...) are BindParams. There are implicit
conversions out there to convert (String, NodeSeq => NodeSeq) to a
FuncBindParam, which makes the nice "name" -> function syntax work.
But you provided (String, NodeSeq => List[Node]), not (String, NodeSeq
=> NodeSeq), so it couldn't find an implicit to apply. You could have
also rewritten to use a FuncBindParam directly rather than apply a
type annotation (not that there's any benefit, just FYI).
e.g.
bind("videos", template, ... FuncBindParam("list", ns =>
resources.flatMap(...)))
-Ross
On Dec 30, 2009, at 3:03 PM, Igor Lev wrote:
> Hmm that _was_ pretty silly. I guess I have to go over the implicits
> section in my Scala notes :)
>
> Thanks for the quick response David.
>
> On Wed, Dec 30, 2009 at 2:19 PM, David Pollak <feeder.of.the.be...@gmail.com
> > wrote:
>
>
> On Wed, Dec 30, 2009 at 11:03 AM, Igor <igor...@gmail.com> wrote:
> Hi everyone,
>
> Long time lurker, first time poster here, I've been trying to pick up
> Lift recently and am stuck with a seemingly simple bind:
> <div>
> <subject:videos>
> <videos:count/> out of <videos:total/> videos
> <videos:list>
> <div>
> <video:name/> <span class="cm"> some text</span>
> </div>
> </videos:list>
> </subject:videos>
> </div>
>
> val length = resources.length
> bind("videos", template,
> "count" -> length,
> "total" -> length,
> "list" -> {(ns: NodeSeq) => resources.flatMap(c => bind("video",
> ns,
> "name" ->
> <a href="#">{c.displayName}</a>))})
>
>
>
> {(ns: NodeSeq) => (resources.flatMap(c => bind()): NodeSeq)}
>
> That should do it. You have to tell the compiler you want a NodeSeq
> out of the function and the compiler will apply the implicit
> conversion from List[Node] -> NodeSeq
>
> This is throwing the following compiler error:
>
> error: overloaded method value bind with alternatives
> (String,net.liftweb.common.Box[(scala.xml.NodeSeq) =>
> scala.xml.NodeSeq],net.liftweb.common.Box
> [(scala.xml.PrefixedAttribute) =>
> scala.xml.MetaData
> ],scala.xml.NodeSeq,net.liftweb.util.Helpers.BindParam*)
> scala.xml.NodeSeq <and>
> (String,scala.xml.NodeSeq,net.liftweb.util.Helpers.BindParam*)
> scala.xml.NodeSeq cannot be applied to
> (java.lang.String
> ,scala.xml.NodeSeq
> ,net.liftweb.util.Helpers.IntBindParam
> ,net.liftweb.util.Helpers.IntBindParam,
> (String, (scala.xml.NodeSeq) => List[scala.xml.Node]))
> bind("videos", template,
>
>
> Now as far as I can tell the issue is that I'm getting a List
> [scala.xml.Node] out of the flatMap. For some reason I thought I was
> able to do this before but if not should I be doing something else to
> convert it to a NodeSeq instead ?
>
> I basically have a section that I want to populate with some content
> (1 content item per list item) and also stick the length of the list
> in the top of the section.
>
> Not sure if my whole approach is flawed or not, open to any
> suggestions or pointers to the relevant section of TFM.
>
>
> Thanks a lot,
> Igor
>
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