Here is a very simple program which uses the CLR classes to write out the value of the square root of two:

`require 'CLRPackage'`

` `

`import "System"`

` `

`Console = luanet.import_type "System.Console"`

`Math = luanet.import_type "System.Math"`

` `

`Console.WriteLine("sqrt(2) is {0}",Math.Sqrt(2))`

The first task
for any LuaInterface program is to load any assemblies needed, and
the second task is to import the types. In this case, the
`Console`

and
`Math`

classes are loaded
explicitly, and we call their static methods
`WriteLine`

and
`Sqrt`

.LuaInterface
will convert Lua numbers and strings into their .NET equivalents
for us.

Like all hello programs, it is basically silly; the equivalent pure Lua program is of course just this one-liner:

`print("sqrt(2) is "..math.sqrt(2))`

But these techniques will be used to bring all the considerable power of the .NET framework into Lua programs, like the ability to easily write good-looking GUI applications, examine running processes, etc.