diff --git a/lib/engine.js b/lib/engine.js
index 9ac237f..ae4f492 100644
--- a/lib/engine.js
+++ b/lib/engine.js
@@ -1,6 +1,6 @@
 // Generated by CoffeeScript 1.6.1
 (function() {
-  var exports, fromFile, fs, parse, render, tumble;
+  var fromFile, fs, parse, render, tumble;
 
   tumble = require('./lexer').parse;
 
@@ -18,15 +18,21 @@
 
   fromFile = function(path, options, callback) {
     return fs.readFile(path, 'utf8', function(err, str) {
-      if (err) {
-        return callback(err);
+      if (callback) {
+        if (err) {
+          return callback(err);
+        }
+        console.log(str, options);
+        return callback(null, render(str, options, callback));
+      }
+      if (err) {
+        throw err;
       }
-      return render(str, options, callback);
     });
   };
 
   fromFile.render = render;
 
-  exports = fromFile;
+  module.exports = fromFile;
 
 }).call(this);
diff --git a/lib/lexer.js b/lib/lexer.js
index 89973a5..c501c82 100644
--- a/lib/lexer.js
+++ b/lib/lexer.js
@@ -76,37 +76,38 @@ module.exports = (function() {
         peg$c3 = null,
         peg$c4 = ":",
         peg$c5 = "\":\"",
-        peg$c6 = function(b, n) { return {type: b, name: n }; },
-        peg$c7 = "/",
-        peg$c8 = "\"/\"",
-        peg$c9 = "tagname",
-        peg$c10 = /^[a-zA-Z]/,
-        peg$c11 = "[a-zA-Z]",
-        peg$c12 = function(t) { return t.join(''); },
-        peg$c13 = "",
-        peg$c14 = /^[a-zA-Z:\/]/,
-        peg$c15 = "[a-zA-Z:\\/]",
-        peg$c16 = "{",
-        peg$c17 = "\"{\"",
-        peg$c18 = "}",
-        peg$c19 = "\"}\"",
-        peg$c20 = "\n",
-        peg$c21 = "\"\\n\"",
-        peg$c22 = "\r\n",
-        peg$c23 = "\"\\r\\n\"",
-        peg$c24 = "\r",
-        peg$c25 = "\"\\r\"",
-        peg$c26 = "\u2028",
-        peg$c27 = "\"\\u2028\"",
-        peg$c28 = "\u2029",
-        peg$c29 = "\"\\u2029\"",
-        peg$c30 = "any character",
-        peg$c31 = function(c) {return c},
-        peg$c32 = function(bs) { return { unit: 'text', content: bs.join('') } },
-        peg$c33 = "variable",
-        peg$c34 = function(t) { return { unit: 'variable', name: t }; },
-        peg$c35 = function(t, ps, n) { return (t.type == n.type) && (t.name == n.name) },
-        peg$c36 = function(t, ps, n) { return {unit: 'block', type:t.type, name:t.name, content: ps } },
+        peg$c6 = function(b, n) { return is_valid_block_type(b); },
+        peg$c7 = "",
+        peg$c8 = function(b, n) { return {type: b, name: n }; },
+        peg$c9 = "/",
+        peg$c10 = "\"/\"",
+        peg$c11 = "tagname",
+        peg$c12 = /^[a-zA-Z]/,
+        peg$c13 = "[a-zA-Z]",
+        peg$c14 = function(t) { return t.join(''); },
+        peg$c15 = /^[a-zA-Z:\/]/,
+        peg$c16 = "[a-zA-Z:\\/]",
+        peg$c17 = "{",
+        peg$c18 = "\"{\"",
+        peg$c19 = "}",
+        peg$c20 = "\"}\"",
+        peg$c21 = "\n",
+        peg$c22 = "\"\\n\"",
+        peg$c23 = "\r\n",
+        peg$c24 = "\"\\r\\n\"",
+        peg$c25 = "\r",
+        peg$c26 = "\"\\r\"",
+        peg$c27 = "\u2028",
+        peg$c28 = "\"\\u2028\"",
+        peg$c29 = "\u2029",
+        peg$c30 = "\"\\u2029\"",
+        peg$c31 = "any character",
+        peg$c32 = function(c) {return c},
+        peg$c33 = function(bs) { return { unit: 'text', content: bs.join('') } },
+        peg$c34 = "variable",
+        peg$c35 = function(t) { return { unit: 'variable', name: t }; },
+        peg$c36 = function(t, ps, n) { return (t.type == n.type) && (t.name == n.name) },
+        peg$c37 = function(t, ps, n) { return {unit: 'block', type:t.type, name:t.name, content: ps } },
 
         peg$currPos          = 0,
         peg$reportedPos      = 0,
@@ -239,7 +240,7 @@ module.exports = (function() {
     }
 
     function peg$parsetag_start() {
-      var s0, s1, s2, s3, s4, s5;
+      var s0, s1, s2, s3, s4, s5, s6;
 
       peg$silentFails++;
       s0 = peg$currPos;
@@ -259,13 +260,25 @@ module.exports = (function() {
             if (s4 !== null) {
               s5 = peg$parserd();
               if (s5 !== null) {
-                peg$reportedPos = s0;
-                s1 = peg$c6(s2,s4);
-                if (s1 === null) {
-                  peg$currPos = s0;
-                  s0 = s1;
+                peg$reportedPos = peg$currPos;
+                s6 = peg$c6(s2,s4);
+                if (s6) {
+                  s6 = peg$c7;
                 } else {
-                  s0 = s1;
+                  s6 = peg$c3;
+                }
+                if (s6 !== null) {
+                  peg$reportedPos = s0;
+                  s1 = peg$c8(s2,s4);
+                  if (s1 === null) {
+                    peg$currPos = s0;
+                    s0 = s1;
+                  } else {
+                    s0 = s1;
+                  }
+                } else {
+                  peg$currPos = s0;
+                  s0 = peg$c3;
                 }
               } else {
                 peg$currPos = s0;
@@ -303,11 +316,11 @@ module.exports = (function() {
       s1 = peg$parseld();
       if (s1 !== null) {
         if (input.charCodeAt(peg$currPos) === 47) {
-          s2 = peg$c7;
+          s2 = peg$c9;
           peg$currPos++;
         } else {
           s2 = null;
-          if (peg$silentFails === 0) { peg$fail(peg$c8); }
+          if (peg$silentFails === 0) { peg$fail(peg$c10); }
         }
         if (s2 !== null) {
           s3 = peg$parsetagname();
@@ -325,7 +338,7 @@ module.exports = (function() {
                 s6 = peg$parserd();
                 if (s6 !== null) {
                   peg$reportedPos = s0;
-                  s1 = peg$c6(s3,s5);
+                  s1 = peg$c8(s3,s5);
                   if (s1 === null) {
                     peg$currPos = s0;
                     s0 = s1;
@@ -366,22 +379,22 @@ module.exports = (function() {
       peg$silentFails++;
       s0 = peg$currPos;
       s1 = [];
-      if (peg$c10.test(input.charAt(peg$currPos))) {
+      if (peg$c12.test(input.charAt(peg$currPos))) {
         s2 = input.charAt(peg$currPos);
         peg$currPos++;
       } else {
         s2 = null;
-        if (peg$silentFails === 0) { peg$fail(peg$c11); }
+        if (peg$silentFails === 0) { peg$fail(peg$c13); }
       }
       if (s2 !== null) {
         while (s2 !== null) {
           s1.push(s2);
-          if (peg$c10.test(input.charAt(peg$currPos))) {
+          if (peg$c12.test(input.charAt(peg$currPos))) {
             s2 = input.charAt(peg$currPos);
             peg$currPos++;
           } else {
             s2 = null;
-            if (peg$silentFails === 0) { peg$fail(peg$c11); }
+            if (peg$silentFails === 0) { peg$fail(peg$c13); }
           }
         }
       } else {
@@ -389,7 +402,7 @@ module.exports = (function() {
       }
       if (s1 !== null) {
         peg$reportedPos = s0;
-        s1 = peg$c12(s1);
+        s1 = peg$c14(s1);
       }
       if (s1 === null) {
         peg$currPos = s0;
@@ -400,7 +413,7 @@ module.exports = (function() {
       peg$silentFails--;
       if (s0 === null) {
         s1 = null;
-        if (peg$silentFails === 0) { peg$fail(peg$c9); }
+        if (peg$silentFails === 0) { peg$fail(peg$c11); }
       }
 
       return s0;
@@ -419,7 +432,7 @@ module.exports = (function() {
         s5 = peg$parserd();
         peg$silentFails--;
         if (s5 === null) {
-          s4 = peg$c13;
+          s4 = peg$c7;
         } else {
           peg$currPos = s4;
           s4 = peg$c3;
@@ -430,18 +443,18 @@ module.exports = (function() {
           s6 = peg$parseeol();
           peg$silentFails--;
           if (s6 === null) {
-            s5 = peg$c13;
+            s5 = peg$c7;
           } else {
             peg$currPos = s5;
             s5 = peg$c3;
           }
           if (s5 !== null) {
-            if (peg$c14.test(input.charAt(peg$currPos))) {
+            if (peg$c15.test(input.charAt(peg$currPos))) {
               s6 = input.charAt(peg$currPos);
               peg$currPos++;
             } else {
               s6 = null;
-              if (peg$silentFails === 0) { peg$fail(peg$c15); }
+              if (peg$silentFails === 0) { peg$fail(peg$c16); }
             }
             if (s6 !== null) {
               s4 = [s4, s5, s6];
@@ -467,7 +480,7 @@ module.exports = (function() {
             s5 = peg$parserd();
             peg$silentFails--;
             if (s5 === null) {
-              s4 = peg$c13;
+              s4 = peg$c7;
             } else {
               peg$currPos = s4;
               s4 = peg$c3;
@@ -478,18 +491,18 @@ module.exports = (function() {
               s6 = peg$parseeol();
               peg$silentFails--;
               if (s6 === null) {
-                s5 = peg$c13;
+                s5 = peg$c7;
               } else {
                 peg$currPos = s5;
                 s5 = peg$c3;
               }
               if (s5 !== null) {
-                if (peg$c14.test(input.charAt(peg$currPos))) {
+                if (peg$c15.test(input.charAt(peg$currPos))) {
                   s6 = input.charAt(peg$currPos);
                   peg$currPos++;
                 } else {
                   s6 = null;
-                  if (peg$silentFails === 0) { peg$fail(peg$c15); }
+                  if (peg$silentFails === 0) { peg$fail(peg$c16); }
                 }
                 if (s6 !== null) {
                   s4 = [s4, s5, s6];
@@ -535,11 +548,11 @@ module.exports = (function() {
       var s0;
 
       if (input.charCodeAt(peg$currPos) === 123) {
-        s0 = peg$c16;
+        s0 = peg$c17;
         peg$currPos++;
       } else {
         s0 = null;
-        if (peg$silentFails === 0) { peg$fail(peg$c17); }
+        if (peg$silentFails === 0) { peg$fail(peg$c18); }
       }
 
       return s0;
@@ -549,11 +562,11 @@ module.exports = (function() {
       var s0;
 
       if (input.charCodeAt(peg$currPos) === 125) {
-        s0 = peg$c18;
+        s0 = peg$c19;
         peg$currPos++;
       } else {
         s0 = null;
-        if (peg$silentFails === 0) { peg$fail(peg$c19); }
+        if (peg$silentFails === 0) { peg$fail(peg$c20); }
       }
 
       return s0;
@@ -563,43 +576,43 @@ module.exports = (function() {
       var s0;
 
       if (input.charCodeAt(peg$currPos) === 10) {
-        s0 = peg$c20;
+        s0 = peg$c21;
         peg$currPos++;
       } else {
         s0 = null;
-        if (peg$silentFails === 0) { peg$fail(peg$c21); }
+        if (peg$silentFails === 0) { peg$fail(peg$c22); }
       }
       if (s0 === null) {
-        if (input.substr(peg$currPos, 2) === peg$c22) {
-          s0 = peg$c22;
+        if (input.substr(peg$currPos, 2) === peg$c23) {
+          s0 = peg$c23;
           peg$currPos += 2;
         } else {
           s0 = null;
-          if (peg$silentFails === 0) { peg$fail(peg$c23); }
+          if (peg$silentFails === 0) { peg$fail(peg$c24); }
         }
         if (s0 === null) {
           if (input.charCodeAt(peg$currPos) === 13) {
-            s0 = peg$c24;
+            s0 = peg$c25;
             peg$currPos++;
           } else {
             s0 = null;
-            if (peg$silentFails === 0) { peg$fail(peg$c25); }
+            if (peg$silentFails === 0) { peg$fail(peg$c26); }
           }
           if (s0 === null) {
             if (input.charCodeAt(peg$currPos) === 8232) {
-              s0 = peg$c26;
+              s0 = peg$c27;
               peg$currPos++;
             } else {
               s0 = null;
-              if (peg$silentFails === 0) { peg$fail(peg$c27); }
+              if (peg$silentFails === 0) { peg$fail(peg$c28); }
             }
             if (s0 === null) {
               if (input.charCodeAt(peg$currPos) === 8233) {
-                s0 = peg$c28;
+                s0 = peg$c29;
                 peg$currPos++;
               } else {
                 s0 = null;
-                if (peg$silentFails === 0) { peg$fail(peg$c29); }
+                if (peg$silentFails === 0) { peg$fail(peg$c30); }
               }
             }
           }
@@ -620,7 +633,7 @@ module.exports = (function() {
       s4 = peg$parsetag();
       peg$silentFails--;
       if (s4 === null) {
-        s3 = peg$c13;
+        s3 = peg$c7;
       } else {
         peg$currPos = s3;
         s3 = peg$c3;
@@ -631,11 +644,11 @@ module.exports = (function() {
           peg$currPos++;
         } else {
           s4 = null;
-          if (peg$silentFails === 0) { peg$fail(peg$c30); }
+          if (peg$silentFails === 0) { peg$fail(peg$c31); }
         }
         if (s4 !== null) {
           peg$reportedPos = s2;
-          s3 = peg$c31(s4);
+          s3 = peg$c32(s4);
           if (s3 === null) {
             peg$currPos = s2;
             s2 = s3;
@@ -659,7 +672,7 @@ module.exports = (function() {
           s4 = peg$parsetag();
           peg$silentFails--;
           if (s4 === null) {
-            s3 = peg$c13;
+            s3 = peg$c7;
           } else {
             peg$currPos = s3;
             s3 = peg$c3;
@@ -670,11 +683,11 @@ module.exports = (function() {
               peg$currPos++;
             } else {
               s4 = null;
-              if (peg$silentFails === 0) { peg$fail(peg$c30); }
+              if (peg$silentFails === 0) { peg$fail(peg$c31); }
             }
             if (s4 !== null) {
               peg$reportedPos = s2;
-              s3 = peg$c31(s4);
+              s3 = peg$c32(s4);
               if (s3 === null) {
                 peg$currPos = s2;
                 s2 = s3;
@@ -695,7 +708,7 @@ module.exports = (function() {
       }
       if (s1 !== null) {
         peg$reportedPos = s0;
-        s1 = peg$c32(s1);
+        s1 = peg$c33(s1);
       }
       if (s1 === null) {
         peg$currPos = s0;
@@ -719,7 +732,7 @@ module.exports = (function() {
           s3 = peg$parserd();
           if (s3 !== null) {
             peg$reportedPos = s0;
-            s1 = peg$c34(s2);
+            s1 = peg$c35(s2);
             if (s1 === null) {
               peg$currPos = s0;
               s0 = s1;
@@ -741,7 +754,7 @@ module.exports = (function() {
       peg$silentFails--;
       if (s0 === null) {
         s1 = null;
-        if (peg$silentFails === 0) { peg$fail(peg$c33); }
+        if (peg$silentFails === 0) { peg$fail(peg$c34); }
       }
 
       return s0;
@@ -763,15 +776,15 @@ module.exports = (function() {
           s3 = peg$parsetag_end();
           if (s3 !== null) {
             peg$reportedPos = peg$currPos;
-            s4 = peg$c35(s1,s2,s3);
+            s4 = peg$c36(s1,s2,s3);
             if (s4) {
-              s4 = peg$c13;
+              s4 = peg$c7;
             } else {
               s4 = peg$c3;
             }
             if (s4 !== null) {
               peg$reportedPos = s0;
-              s1 = peg$c36(s1,s2,s3);
+              s1 = peg$c37(s1,s2,s3);
               if (s1 === null) {
                 peg$currPos = s0;
                 s0 = s1;
@@ -798,6 +811,20 @@ module.exports = (function() {
       return s0;
     }
 
+
+        var _VALID_BLOCK_TYPES = ['if', 'when', 'template', 'many', 'each', 'block'];
+        var _VBT_LENGTH = _VALID_BLOCK_TYPES.length;
+
+        function is_valid_block_type(b) {
+            for(i = 0; i < _VBT_LENGTH; i++) {
+                if (_VALID_BLOCK_TYPES[i] == b) {
+                    return true;
+                }
+            }
+            return false;
+        }
+
+
     peg$result = peg$startRuleFunction();
 
     if (peg$result !== null && peg$currPos === input.length) {
diff --git a/lib/parser.js b/lib/parser.js
index a5f8b34..df06619 100644
--- a/lib/parser.js
+++ b/lib/parser.js
@@ -64,7 +64,7 @@
       return r;
     };
 
-    Contexter.prototype["if"] = function(name, cb) {
+    Contexter.prototype.when = function(name, cb) {
       var p;
       p = this.has_any_one(name);
       if (p) {
@@ -74,6 +74,16 @@
       }
     };
 
+    Contexter.prototype["if"] = function(name, cb) {
+      var p;
+      p = this.has(name);
+      if (p) {
+        return cb(this);
+      } else {
+        return '';
+      }
+    };
+
     Contexter.prototype.block = function(name, cb) {
       var p;
       p = this.has_any_one(name);
diff --git a/src/engine.coffee b/src/engine.coffee
index 67d8f8c..21aad69 100644
--- a/src/engine.coffee
+++ b/src/engine.coffee
@@ -10,9 +10,12 @@ render = (str, options, callback) ->
 
 fromFile = (path, options, callback) ->
     fs.readFile path, 'utf8', (err, str) ->
-        return callback(err) if err
-        render(str, options, callback)
+        if callback
+            return callback(err) if err
+            console.log(str, options);
+            return callback(null, render(str, options, callback))
+        throw err if err
 
 fromFile.render = render
 
-exports = fromFile
+module.exports = fromFile
diff --git a/src/lexer.peg b/src/lexer.peg
index 17d5423..35586d3 100644
--- a/src/lexer.peg
+++ b/src/lexer.peg
@@ -1,4 +1,18 @@
 // -*- mode: javascript -*-
+{
+    var _VALID_BLOCK_TYPES = ['if', 'when', 'template', 'many', 'each', 'block'];
+    var _VBT_LENGTH = _VALID_BLOCK_TYPES.length;
+
+    function is_valid_block_type(b) {
+        for(i = 0; i < _VBT_LENGTH; i++) {
+            if (_VALID_BLOCK_TYPES[i] == b) {
+                return true;
+            }
+        }
+        return false;
+    }
+}
+
 
 document
     = ps:part* 
@@ -9,6 +23,7 @@ part
 
 tag_start "tag_start"
     =  ld b:tagname ":" n:tagname rd
+    &{ return is_valid_block_type(b); }
     { return {type: b, name: n }; }
 
 tag_end
diff --git a/src/parser.coffee b/src/parser.coffee
index a6a3429..ad2a645 100644
--- a/src/parser.coffee
+++ b/src/parser.coffee
@@ -39,12 +39,18 @@ class Contexter
         @depth--
         r
 
-    if: (name, cb) ->
-        # Execute and return this specifiecd block if and only if the
+    when: (name, cb) ->
+        # Execute and return this specified block if and only if the
         # requested context is valid.
         p = @has_any_one(name)
         if p then cb(@) else ''
 
+    if: (name, cb) ->
+        # Execute and return this specifiecd block if and only if the
+        # requested context is valid AND current
+        p = @has(name)
+        if p then cb(@) else ''
+
     block: (name, cb) ->
         # Execute and return this specified block if and only if the
         # requested context is valid and entrant.