A bit more cleanup.

TODO

@@ -1,9 +1,7 @@
-- We should allow leaf nodes of the template tree to be zero-argument
-  functions.
 - We should allow some way of passing variables or data down the tree.
 
-Doing both of the above would allow us, at least in English, to remove the
-hacky prefix-stripping we currently do on days of the week and let us pass a
+Doing the above would allow us, at least in English, to remove the hacky
+prefix-stripping we currently do on days of the week and let us pass a
 "use_preposition" flag to them:
 
     "morning": function() {

lib/template.js

@@ -7,12 +7,24 @@ module.exports = function(template) {
       if(!template.hasOwnProperty(expr))
         throw new Error("\"" + expr + "\" not found in language template.");
 
-      else if(typeof template[expr] !== "string" ||
-              /\$\d+/.test(template[expr]))
-        throw new Error("\"" + expr + "\" was used in a value context, but is expected in a template context.");
+      else if(typeof template[expr] === "string") {
+        if(/\$\d+/.test(template[expr]))
+          throw new Error("\"" + expr + "\" was used in a value context, but is expected in a template context.");
+
+        else
+          return template[expr];
+      }
+
+      else if(typeof template[expr] === "function") {
+        if(template[expr].length !== 0)
+          throw new Error("\"" + expr + "\" was used in a value context, but is expected in a template context.");
+
+        else
+          return template[expr]();
+      }
 
       else
-        return template[expr];
+        throw new Error("\"" + expr + "\" is not a valid language template pattern.");
     }
 
     else if(Array.isArray(expr) &&

test.js

@@ -10,7 +10,8 @@ describe("translation", function() {
     var convert = template({
           "foo": "bar",
           "bar": "meeple $2",
-          "baz": function(a, b) { return "meeple " + b; }
+          "baz": function(a, b) { return "meeple " + b; },
+          "quux": function() { return "glorple"; }
         });
 
     it("should return a number in string form", function() {
@@ -62,6 +63,14 @@ describe("translation", function() {
     it("should throw an error given an object", function() {
       expect(function() { convert({}); }).to.throw();
     });
+
+    it("should apply an expected value conversion given a zero-argument function", function() {
+      expect(convert("quux")).to.equal("glorple");
+    });
+
+    it("should fail to apply a function template given a value", function() {
+      expect(function() { convert("baz"); }).to.throw();
+    });
   });
 
   describe("language", function() {