Dictionary as private field in Script# class

Question

I have the following class in script# 0.7.5:

[ScriptNamespace("Scripts")]
public class MyClass 
{
    private Dictionary<string, string> stageMapping = new Dictionary<string, string>();

    public PortfolioOptimisationOverlord()
    {
        stageMapping["first"] = "http://www.me.com/mike";
        stageMapping["second"] = "http://www.me.com/terry";
        stageMapping["third"] = "http://www.me.com/billy";
        stageMapping["fourth"] = "http://www.me.com/bobby";
        stageMapping["fifth"] = "http://www.me.com/richard";
    }
}

unfortunately when compiled it doesn't produce a prototype class so fails saying that it can't access this.

If I make a private field of type int it seems to work, but not with dictionarys or lists.

--EDIT--
here's some more information: The javascript produced by this is:

////////////////////////////////////////////////////////////////////////////////
// Scripts.PortfolioOptimisationOverlord

Scripts.PortfolioOptimisationOverlord = function Scripts_PortfolioOptimisationOverlord() {
    /// <field name="_stageMapping" type="Object">
    /// </field>
    this._stageMapping = {};
    this._stageMapping['first'] = 'http://www.me.com/mike';
    this._stageMapping['second'] = 'http://www.me.com/terry';
    this._stageMapping['third'] = 'http://www.me.com/billy';
    this._stageMapping['fourth'] = 'http://www.me.com/bobby';
    this._stageMapping['fifth'] = 'http://www.me.com/richard';
}

If I add an int private field called intField:

 ////////////////////////////////////////////////////////////////////////////////
// Scripts.PortfolioOptimisationOverlord

Scripts.PortfolioOptimisationOverlord = function Scripts_PortfolioOptimisationOverlord() {
    /// <field name="_stageMapping" type="Object">
    /// </field>
    /// <field name="_intField" type="Number" integer="true">
    /// </field>
    this._stageMapping = {};
    this._stageMapping['first'] = 'http://www.me.com/mike';
    this._stageMapping['second'] = 'http://www.me.com/terry';
    this._stageMapping['third'] = 'http://www.me.com/billy';
    this._stageMapping['fourth'] = 'http://www.me.com/bobby';
    this._stageMapping['fifth'] = 'http://www.me.com/richard';
}
Scripts.PortfolioOptimisationOverlord.prototype = {
    _intField: 0
}

as you can see the only change is the addition of a type with .prototype on the end.

it fails on construction.

Answer 1

It seems that 0.8 was the answer. Thanks to all who offered help.