5 files changed, 21 insertions, 3 deletions
diff --git a/lib/js/urweb.js b/lib/js/urweb.js
index d3c144b9..4a447a5b 100644
--- a/lib/js/urweb.js
+++ b/lib/js/urweb.js
@@ -154,6 +154,10 @@ function pfl(s) {
     throw "Can't parse float: " + s;
 }
 
+function cat(s1, s2) {
+  return s1 + s2;
+}
+
 function whine(msg) {
   alert(msg);
   throw msg;
diff --git a/lib/ur/basis.urs b/lib/ur/basis.urs
index 586c5ef9..f95e8eba 100644
--- a/lib/ur/basis.urs
+++ b/lib/ur/basis.urs
@@ -375,8 +375,8 @@ con form = [Body, Form]
 con tabl = [Body, Table]
 con tr = [Body, Tr]
 
-val dyn : ctx ::: {Unit} -> use ::: {Type} -> bind ::: {Type} -> unit
-          -> tag [Signal = signal (xml ctx use bind)] ctx [] use bind
+val dyn : use ::: {Type} -> bind ::: {Type} -> unit
+          -> tag [Signal = signal (xml body use bind)] body [] use bind
 
 val head : unit -> tag [] html head [] []
 val title : unit -> tag [] head [] [] []
@@ -393,6 +393,8 @@ con bodyTagStandalone = fn (attrs :: {Type}) =>
 
 val br : bodyTagStandalone []
 
+val span : bodyTag []
+
 val p : bodyTag []
 val b : bodyTag []
 val i : bodyTag []
diff --git a/src/jscomp.sml b/src/jscomp.sml
index a487eeab..934b9945 100644
--- a/src/jscomp.sml
+++ b/src/jscomp.sml
@@ -49,7 +49,8 @@ val funcs = [(("Basis", "alert"), "alert"),
              (("Basis", "urlifyInt"), "ts"),
              (("Basis", "urlifyFloat"), "ts"),
              (("Basis", "urlifyString"), "uf"),
-             (("Basis", "recv"), "rv")]
+             (("Basis", "recv"), "rv"),
+             (("Basis", "strcat"), "cat")]
 
 structure FM = BinaryMapFn(struct
                            type ord_key = string * string
diff --git a/tests/dynSpan.ur b/tests/dynSpan.ur
new file mode 100644
index 00000000..123adde2
--- /dev/null
+++ b/tests/dynSpan.ur
@@ -0,0 +1,8 @@
+val x = 1
+
+fun main () : transaction page =
+    s <- source "!";
+    return <xml><body>
+      <dyn signal={x <- signal s; return <xml><span>{[x]}</span></xml>}/>
+      <button onclick={x <- get s; set s (x ^ "!")}/>
+    </body></xml>
diff --git a/tests/dynSpan.urp b/tests/dynSpan.urp
new file mode 100644
index 00000000..611dc313
--- /dev/null
+++ b/tests/dynSpan.urp
@@ -0,0 +1,3 @@
+debug
+
+dynSpan