--- a/spec/latest/json-ld-api/index.html Sun Oct 16 18:57:13 2011 -0400
+++ b/spec/latest/json-ld-api/index.html Thu Oct 20 16:52:00 2011 -0700
@@ -955,6 +955,8 @@
</ol>
</section>
+<p class="issue">What are the implications for expanding lists?</p>
+
</section>
<section>
@@ -986,6 +988,8 @@
</ol>
</section>
+<p class="issue">What are the implications for compacting lists?</p>
+
</section>
@@ -1182,6 +1186,8 @@
</section>
+<p class="issue">What are the implications for framing lists?</p>
+
</section>
<section>
@@ -2341,6 +2347,10 @@
</li>
</ol>
</li>
+ <li>
+ If the <tref>JSON object</tref> has a <code>@list</code> key and the value is an <tref>array</tref>
+ process the value as a list starting at <a href="#processing-step-list">Step 4</a>.
+ </li>
<li id="processing-step-subject">If the <tref>JSON object</tref> has a <code>@subject</code> key:
<ol class="algorithm">
<li>
@@ -2350,10 +2360,20 @@
<tref>active object</tref>. Set the <tref>active subject</tref> to the <tref>active object</tref>.
</li>
<li>
- Create a new <tref>processor state</tref> using copies of the <tref>active context</tref>,
- <tref>active subject</tref> and <tref>active property</tref> and process the value
- starting at <a href="#processing-step-associative">Step 2</a>, set the <tref>active
- subject</tref> to the result and proceed using the previous <tref>processor state</tref>.
+ Create a new <tref>processor state</tref> copies of the <tref>active context</tref>,
+ <tref>active subject</tref> and <tref>active property</tref>.
+ <ol class="algorithm">
+ <li>
+ If the <tref>active property</tref> is the target of a <code>@list</code> coercion,
+ and the value is an <tref>array</tref>,
+ process the value as a list starting at <a href="#processing-step-list">Step 4</a>.
+ </li>
+ <li>
+ Otherwise, process the value starting at
+ <a href="#processing-step-associative">Step 2</a>.
+ </li>
+ <li>Proceed using the previous <tref>processor state</tref>.</li>
+ </ol>
</li>
</ol>
</li>
@@ -2402,6 +2422,31 @@
</ol>
</li>
+ <li id="processing-step-list">
+ Generate an RDF List by linking
+ each element of the list using <code>rdf:first</code> and <code>rdf:next</code>, terminating the list with <code>rdf:nil</code>
+ using the following sequence:
+ <ol class="algorithm">
+ <li>
+ If the list has no element, generate a triple using the <tref>active subject</tref>, <tref>active property</tref>
+ and <code>rdf:nil</code>.
+ </li>
+ <li>
+ Otherwise, generate a triple using using the <tref>active subject</tref>, <tref>active property</tref>
+ and a newly generated BNode identified as <em>first <tdef>blank node identifier</tdef></em>.
+ </li>
+ <li>
+ For each element other than the last element in the list:
+ <ol class="algorithm">
+ <li>Create a processor state using the active context, <em>first <tdef>blank node identifier</tdef></em> as the <tref>active subject</tref>, and <code>rdf:first</code> as the <tref>active property</tref>.</li>
+ <li>Unless this is the last element in the list, generate a new BNode identified as <em>rest <tdef>blank node identifier</tdef></em>, otherwise use <code>rdf:nil</code>.</li>
+ <li>Generate a new triple using <em>first <tdef>blank node identifier</tdef></em>, <code>rdf:rest</code> and <em>rest <tdef>blank node identifier</tdef></em>.</li>
+ <li>Set <em>first <tdef>blank node identifier</tdef></em> to <em>rest <tdef>blank node identifier</tdef></em>.</li>
+ </ol>
+ </li>
+ </ol>
+ </li>
+
<li>
If a <tref>string</tref> is detected:
<ol class="algorithm">
--- a/spec/latest/json-ld-syntax/index.html Sun Oct 16 18:57:13 2011 -0400
+++ b/spec/latest/json-ld-syntax/index.html Thu Oct 20 16:52:00 2011 -0700
@@ -1695,6 +1695,92 @@
</section>
<section>
+ <h2>Lists</h2>
+ <p>
+ Because graphs do not describe ordering for links between nodes, in contrast to plain JSON, multi-valued properties
+ in JSON-LD do not provide an ordering of the listed objects. For example, consider the following
+ simple document:
+ </p>
+ <pre class="example" data-transform="updateExample">
+ <!--
+ {
+ ...
+ "@subject": "http://example.org/people#joebob",
+ "nick": ****["joe", "bob", "jaybee"]****,
+ ...
+ }
+ -->
+ </pre>
+ <p>
+ This results in three triples being generated, each relating the subject to an individual
+ object, with no inherent order.</p>
+ <p>To preserve the order of the objects, RDF-based languages, such as [[TURTLE]]
+ use the concept of an <code>rdf:List</code> (as described in [[RDF-SCHEMA]]). This uses a sequence
+ of unlabeled nodes with properties describing a value, a null-terminated next property. Without
+ specific syntactical support, this could be represented in JSON-LD as follows:
+ </p>
+ <pre class="example" data-transform="updateExample">
+ <!--
+ {
+ ...
+ "@subject": "http://example.org/people#joebob",
+ "nick": ****{****,
+ ****"@first": "joe"****,
+ ****"@rest": {****
+ ****"@first": "bob"****,
+ ****"@rest": {****
+ ****"@first": "jaybee"****,
+ ****"@rest": "@nil"****
+ ****}****
+ ****}****
+ ****}****
+ ****}****,
+ ...
+ }
+ -->
+ </pre>
+ <p>
+ As this notation is rather unwieldy and the notion of ordered collections is rather important
+ in data modeling, it is useful to have specific language support. In JSON-LD, a list may
+ be represented using the <code>@list</code> keyword as follows:
+ </p>
+ <pre class="example" data-transform="updateExample">
+ <!--
+ {
+ ...
+ "@subject": "http://example.org/people#joebob",
+ "foaf:nick": ****{"@list": ["joe", "bob", "jaybee"]}****,
+ ...
+ }
+ -->
+ </pre>
+ <p>
+ This describes the use of this <tref>array</tref> as being ordered, and order is maintained through
+ normalization and RDF conversion. If every use of a given multi-valued property is a
+ list, this may be abbreviated by adding an <code>@coerce</code> term:
+ </p>
+ <pre class="example" data-transform="updateExample">
+ <!--
+ {
+ ****"@context": {****
+ ...
+ ****"@coerce": {****
+ ****"@list": ["foaf:nick"]****
+ ****}****
+ ****}****,
+ ...
+ "@subject": "http://example.org/people#joebob",
+ "foaf:nick": ****["joe", "bob", "jaybee"]****,
+ ...
+ }
+ -->
+ </pre>
+ <p>
+ The @list keyword can be used within the <code>@coerce</code> section of a <code>@context</code> to
+ cause value arrays to be coerced into an ordered list.
+ </p>
+</section>
+<section>
<h2>Normalization</h2>
<p>Normalization is the process of taking <tref>JSON-LD input</tref> and