diff --git a/npm-shrinkwrap.json b/npm-shrinkwrap.json
new file mode 100644
index 0000000..d14e80a
--- /dev/null
+++ b/npm-shrinkwrap.json
@@ -0,0 +1,41 @@
+{
+  "name" : "jinjs",
+  "version" : "0.3.6",
+  "dependencies" : {
+    "optimist" : {
+      "version" : "0.2.3",
+      "dependencies" : {
+        "wordwrap" : {
+          "version" : "0.0.2"
+        }
+      }
+    },
+    "pegco" : {
+      "version" : "0.0.1",
+      "dependencies" : {
+        "pegjs" : {
+          "version" : "0.6.2"
+        }
+      }
+    },
+    "coco" : {
+      "version" : "0.6.7"
+    },
+    "rbuild" : {
+      "version" : "0.0.5",
+      "dependencies" : {
+        "async" : {
+          "version" : "0.1.22"
+        }
+      }
+    },
+    "vows" : {
+      "version" : "0.6.3",
+      "dependencies" : {
+        "eyes" : {
+          "version" : "0.1.7"
+        }
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/src/environment.co b/src/environment.co
index 50fdebe..9903240 100644
--- a/src/environment.co
+++ b/src/environment.co
@@ -12,6 +12,8 @@ class Environment
         return eval t
 
     ({@utils ? require("./utils"), @filters ? require("./filters"), @parser ? new Parser!, @pre_compile_func ? "", @require_exp ? 'require'} ? {}) ->
+        @outputUndefinedVariable = false
+        @outputUndefinedVariableWithBrackets = false
 
     getTemplateFromString: function (str)
         try
@@ -28,7 +30,7 @@ class Environment
         str = @pre_compile_func str if @pre_compile_func
 
         ast = @parser.parse str, compilation_ctx
-        opts = {__indent__: 1, @utils, @filters}
+        opts = {__indent__: 1, @utils, @filters, @outputUndefinedVariable, @outputUndefinedVariableWithBrackets}
 
         compilation_ctx = filters_used: {}
         compilation_ctx <<< {@filters, @utils}
diff --git a/src/expression.pegco b/src/expression.pegco
index f36da77..a9fa239 100644
--- a/src/expression.pegco
+++ b/src/expression.pegco
@@ -1,4 +1,3 @@
-
 ->
     compilation_ctx = arguments[2] ? {}
     compilation_ctx.filters ?= {}
@@ -320,7 +319,7 @@ tag_for
     / key:identifier COMMA value:identifier IN exp:expression -> 
         return key: key, value: value, condition: exp 
 
-tag_let
+tag_set
     = variable_name:identifier ASSIGN expression:expression -> 
         return variable_name: variable_name, expression: expression 
 
diff --git a/src/filters.co b/src/filters.co
index 56ecc83..674aefb 100644
--- a/src/filters.co
+++ b/src/filters.co
@@ -186,13 +186,13 @@ exports import do
         if value < 1024
             return "#{value}"
         if value < 1024 * 1024
-            val = val / 1024
+            val = value / 1024
             unit = "Kb"
         else if value < 1024 * 1024 * 1024
-            val = val / (1024 * 1024)
+            val = value / (1024 * 1024)
             unit = "Mb"
         else
-            val = val / (1024 * 1024 * 1024)
+            val = value / (1024 * 1024 * 1024)
             unit = "Gb"
 
         strval = "#{Math.round val}"
@@ -203,7 +203,7 @@ exports import do
 
     $float: function (value)
         res = parseFloat value
-        return 0.0 if res is NaN
+        return 0.0 if isNaN res
         return res
 
     $forceescape: function (value)
@@ -441,10 +441,21 @@ exports import do
             obj = obj[a]
         return obj
 
-    $reverse: function (arr)
-        new_arr = arr.splice 0
+    $reverse: function (arr, keep_array)
+        keep_array = keep_array or false
+        new_arr = arr
+        if \number is typeof arr
+            new_arr = new_arr.toString()
+            new_arr = new_arr.split("")
+            new_arr = new_arr.splice(0)
+        else if \string is typeof arr
+            new_arr = new_arr.split("")
+            new_arr = new_arr.splice(0)
+        else if arr instanceof Array
+            new_arr = new_arr.splice(0)
+        else throw new Error("Unsupported type \"" + typeof arr + "\" for reverse")
         new_arr.reverse()
-        return new_arr
+        return (if (keep_array) then new_arr else new_arr.join(""))
 
     $round: function (value, precision ? 0, method ? 'common')
         if method is \common
diff --git a/src/helpers.co b/src/helpers.co
index c2f66ec..3bc1271 100644
--- a/src/helpers.co
+++ b/src/helpers.co
@@ -20,5 +20,33 @@ function registerExtension (ext, filter)
 # registerExtension \.pwi, (str) -> pwilang.parse str
 # registerExtension \.pwx, (str) -> pwilang.parse str
 
-exports import { registerExtension }
+/**
+ * Register flag to output undefined variables
+ * @param output: flag to output undefined variable name
+ * @param withBrackets: flag to output undefined variable name with brackets
+ */
+function outputUndefinedVariable (output, withBrackets)
+    output ?= true
+    withBrackets ?= false
+    
+    defaultEnvironment.outputUndefinedVariable = output
+    defaultEnvironment.outputUndefinedVariableWithBrackets = withBrackets
+
+/**
+ * Options for JinJS
+ * @param opts: object where the properties are set
+ */
+function options (opts)
+    opts ?= {}
+    
+    # Check if extensions passed
+    if opts.extensions
+        for index, extension in opts.extensions
+            registerExtension extension.ext, extension.filter
+            
+    # Check if outputUndefinedVariable is defined
+    if opts.outputUndefinedVariable
+        outputUndefinedVariable opts.outputUndefinedVariable, opts.outputUndefinedVariableWithBrackets
+
+exports import { registerExtension, outputUndefinedVariable, options }
 
diff --git a/src/main.co b/src/main.co
index 232a975..e2dbdfc 100644
--- a/src/main.co
+++ b/src/main.co
@@ -1,6 +1,6 @@
 { defaultEnvironment, Environment } = require \./environment
-{ registerExtension } = require \./helpers
+{ registerExtension, outputUndefinedVariable, options } = require \./helpers
 { compile } = require \./express
 
-exports <<< { defaultEnvironment, registerExtension, Environment, compile }
+exports <<< { defaultEnvironment, registerExtension, outputUndefinedVariable, options, Environment, compile }
 
diff --git a/src/nodes.co b/src/nodes.co
index 59c6f29..6b9ae1f 100644
--- a/src/nodes.co
+++ b/src/nodes.co
@@ -1,11 +1,10 @@
-
 { parse:make_expression } = require \./expression
 
 make_parse_rule = (rule_name) ->
     return (contents, ctx) -> make_expression contents, rule_name, ctx
 
 parse_for = make_parse_rule \tag_for
-parse_let = make_parse_rule \tag_let
+parse_set = make_parse_rule \tag_set
 parse_macro = make_parse_rule \tag_macro
 parse_extends = make_expression
 parse_block = make_parse_rule \tag_block
@@ -108,7 +107,12 @@ class NodePrint extends Node
     (specs) -> super ...
 
     compile: function (opts, ctx)
-        return "_res += ((_ref = #{make_expression @contents, ctx}) !== undefined && _ref !== null ? _ref : '').toString();"
+        output = ''
+        if (opts.outputUndefinedVariableWithBrackets)
+            output = "{{#{@contents}}}"
+        else if (opts.outputUndefinedVariable)
+            output = @contents
+        return "_res += ((_ref = #{make_expression @contents, ctx}) !== undefined && _ref !== null ? _ref : '#{output}').toString();"
 
 class NodeTag extends Node
     @tag = \__tag__
@@ -242,13 +246,13 @@ class NodeAbspath extends NodeTag
 /**
  *
  */
-class NodeLet extends NodeTag
-    @tag = \let
+class NodeSet extends NodeTag
+    @tag = \set
 
     (specs) -> super ...
 
     compile: function (opts, ctx)
-        { variable_name, expression } = parse_let @contents, ctx
+        { variable_name, expression } = parse_set @contents, ctx
 
         ctx[variable_name] = true # The variable name is now accessible to the rest of the template.
         return res = "var #{variable_name} = ($$.#{variable_name} = #{expression});"
@@ -452,6 +456,19 @@ class NodeIf extends NodeTagContainer
         }"""
         return res
 
+/**
+ * Raw Node
+ */
+class NodeRaw extends NodeTagContainer
+    @tag = \raw
+    @until = \endraw
+    
+    (specs) ->
+        super ...
+
+    compile : function (opts, ctx)
+        console.dir @
+        return "_res += 'ffs';";
 
 class NodeElseFor extends NodeTagContainer
     @tag = \else
@@ -542,13 +559,14 @@ class NodeFor extends NodeTagContainer
         """
 
 exports <<< {
-    NodeIf, NodeDo, NodeLet, NodeFor, NodeMacro, NodeList, NodeBasic,
+    NodeIf, NodeDo, NodeSet, NodeFor, NodeMacro, NodeList, NodeBasic,
     NodePrint, NodeComment, NodeExtends, NodeInclude, NodeImport, NodeFromImport,
-    NodeContinue, NodeCall
+    NodeContinue, NodeCall, NodeRaw
     default_nodes: do
         \if : NodeIf
         \do : NodeDo
-        \let : NodeLet
+        \set : NodeSet
+        \let : NodeSet #Deprecated
         \for : NodeFor
         \macro : NodeMacro
         \extends : NodeExtends
@@ -560,5 +578,6 @@ exports <<< {
         \continue : NodeContinue
         \break : NodeBreak
         \call : NodeCall
+        \raw : NodeRaw
     }
 
diff --git a/test/parser.co b/test/parser.co
index 327a741..f5403cc 100755
--- a/test/parser.co
+++ b/test/parser.co
@@ -63,8 +63,8 @@ suite = require \vows .describe "Expressions Test Suite"
 
 
 suite.addBatch do
-    "The {% let %} tag": do
-        topic: parse "{% let toto = 1 %}TXT"
+    "The {% set %} tag": do
+        topic: parse "{% set toto = 1 %}TXT"
 
         "Lets us assign to a variable that is later exported": (res) ->
             equal res.ctx.toto, 1
@@ -73,10 +73,10 @@ suite.addBatch do
             equal res.txt, 'TXT'
 
         "does not let us assign to reserved-words variables": (res) ->
-            parseError -> _parse "{% let instanceof = 3 %}"
+            parseError -> _parse "{% set instanceof = 3 %}"
 
         "can have their results even across new lines": ->
-            res = _parse "{% let toto\n=\n 1 %}{{ toto }}"
+            res = _parse "{% set toto\n=\n 1 %}{{ toto }}"
             equal res.txt, "1"
 
     ##
@@ -340,7 +340,7 @@ suite.addBatch do
             equal res.txt, 'foo'
 
         "gets to modify the context": ->
-            included = compile "{% let foo = 'bar' %}"
+            included = compile "{% set foo = 'bar' %}"
             res = _parse "{% include included %}{{ foo }}", foo: "foo", included: included
             equal res.txt, 'bar'
 
@@ -382,22 +382,22 @@ suite.addBatch do
     "The {% import %} tag": do
 
         "allows us to import variables from another template to another": ->
-            imported = compile "{% let foo = 'bar' %}"
+            imported = compile "{% set foo = 'bar' %}"
             res = _parse "{% from imported import foo %}{{ foo }}", imported: imported
             equal res.txt, 'bar'
 
         "allows us to import a whole template as a module": ->
-            imported = compile "{% let foo = 'bar' %}"
+            imported = compile "{% set foo = 'bar' %}"
             res = _parse "{% import imported as imp %}{{ imp.foo }}", imported: imported
             equal res.txt, 'bar'
 
         "by default does not expose the current context to the imported module": ->
-            imported = compile "{% let foo = 'bar' %}"
+            imported = compile "{% set foo = 'bar' %}"
             res = _parse "{% import imported as toto %}{{ foo }}", imported: imported, foo: 'foo'
             equal res.txt, 'foo'
 
         "can pass the context to the imported template": ->
-            imported = compile "{% let foo = bar + 'foo' %}"
+            imported = compile "{% set foo = bar + 'foo' %}"
             res = _parse "{% import imported as toto with context %}{{ toto.foo }}", imported: imported, bar: 'bar'
             equal res.txt, 'barfoo'
 
diff --git a/test/templates/test-include.tpl b/test/templates/test-include.tpl
index 662887d..e84566f 100644
--- a/test/templates/test-include.tpl
+++ b/test/templates/test-include.tpl
@@ -1,4 +1,4 @@
-{% let variable = "bloup" %}
+{% set variable = "bloup" %}
 {% macro test () %}
 Yoyo {{ variable }}
 {% endmacro %}