From a02865d8b14636a57e7678d4c883e8b5334c8844 Mon Sep 17 00:00:00 2001
From: Mike Gerwitz <gerwitzm@lovullo.com>
Date: Mon, 24 Nov 2014 15:41:32 -0500
Subject: [PATCH] May now partially apply partial applications

---
 src/apply/partial.xsl    | 20 ++++++++++++++++----
 test/apply/partial.xspec | 21 +++++++++++++++++++++
 tools/xspec              |  2 +-
 3 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/src/apply/partial.xsl b/src/apply/partial.xsl
index 14ad561..ae59d9b 100644
--- a/src/apply/partial.xsl
+++ b/src/apply/partial.xsl
@@ -39,21 +39,33 @@
   the dynamic function calls will handle currying/partial application
   for you, which has a much more inviting syntax.
 
-  TODO: Accept partial application as FNREF.
+  Partially applied functions may continue to be partially applied
+  until their parameters are exhausted.  This can be used to implement
+  currying.
 -->
 <function name="f:partial">
-  <param name="fnref" as="element(f:ref)" />
+  <param name="fnref" as="item()+" />
   <param name="args"  as="item()*" />
 
+  <!-- perform type check here, not above, since we can be passed a
+       sequence (e.g.a  partially applied function) -->
+  <variable name="ref"
+            as="element(f:ref)"
+            select="$fnref[ 1 ]" />
+
   <f:ref>
-    <sequence select="$fnref/@*" />
+    <sequence select="$ref/@*" />
 
     <attribute name="partial"
                select="count( $args )" />
 
-    <sequence select="$fnref/*" />
+    <sequence select="$ref/*" />
   </f:ref>
 
+  <!-- include any previously applied arguments (if we're partially
+       applying a partial application) -->
+  <sequence select="remove( $fnref, 1 )" />
+
   <!-- nested sequences are implicitly flattened, so we're not
        returning a sub-sequence here -->
   <sequence select="$args" />
diff --git a/test/apply/partial.xspec b/test/apply/partial.xspec
index 8f0df53..e6e8c1e 100644
--- a/test/apply/partial.xspec
+++ b/test/apply/partial.xspec
@@ -94,6 +94,27 @@
       <expect label="returns all arguments"
               test="count( $x:result ) = 4" />
     </scenario>
+
+
+    <!-- partial applications should behave as their own functions -->
+    <scenario label="partially applying partial application">
+      <call function="f:partial">
+        <param name="fnref" select="f:partial( $fnref, (1, 2) )" />
+        <param name="args"  select="3" />
+      </call>
+
+      <expect label="returns FNREF as first item in sequence"
+              test="$x:result[ 1 ] = $fnref" />
+
+      <expect label="returns arguments from both partial applications"
+              test="count( $x:result ) = 4" />
+
+      <expect label="arguments are ordered with previous applications
+                     first in sequence"
+              test="$x:result[ 2 ] = 1
+                    and $x:result[ 3 ] = 2
+                    and $x:result[ 4 ] = 3" />
+    </scenario>
   </scenario>
 
 
diff --git a/tools/xspec b/tools/xspec
index 3dc0ab2..20c6b8a 160000
--- a/tools/xspec
+++ b/tools/xspec
@@ -1 +1 @@
-Subproject commit 3dc0ab2e1b78dae5d31c228c22a7dd8868d5678f
+Subproject commit 20c6b8a32f37a6511698fe89b78b82fd1aa64bd2