Working on a project that uses some IronPython scripts to as plug-ins, that utilize functionality coded in C#. In one of my C# classes, I have a property that is of type:

Dictionary<int, float>

I set the value of that property from the IronPython code, like this:

mc = MyClass()
mc.ValueDictionary = Dictionary[int, float]({1:0.0, 2:0.012, 3:0.024})

However, when this bit of code is run, it throws the following exception:

Microsoft.Scripting.ArgumentTypeException was unhandled by user code
  Message=expected Dictionary[int, Single], got Dictionary[int, float]

To make things weirder, originally the C# code used

Dictionary<int, double>

but I could not find a "double" type in IronPython, tried "float" on a whim and it worked fine, giving no errors. But now that it's using float on both ends (which it should have been using from the start) it errors, and thinks that the C# code is using the "Single" data type?!

I've even checked in the object browser for the C# library and, sure enough, it shows as using a "float" type and not "Single"