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Welcome to the LENS documentation page!

LENS is an embedded scripting language for .NET applications. It provides interconnection between the script and your host application.

Adding LENS to your app

Just a few simple steps:

1. Reference LENS.dll in your solution
2. Create an instance of the LensCompiler class and set some properties.
3. Compile the string into a runnable object using Compile method.
4. Run it!

try
{
    var x = 21;
    var y = 2;
    var result = 0;

    var cp = new LensCompiler();
    cp.RegisterProperty("x", () => x);
    cp.RegisterProperty("y", () => y);
    cp.RegisterProperty("res", () => result, r => result = r);

    var source = "res = x * y";
    var compiled = cp.Compile(source);
    compiled.Run();

    Console.WriteLine("The result is {0}", result);
}
catch(LensCompilerException e)
{
    Console.WriteLine("An error has occured: {0}", e.FullMessage);
}

The LENS language

The language itself is influenced by functional languages, such as F#. Its syntax is designed to be lightweight and conscise, while allowing you to interact with any existing .NET types and entities.

Here are a few examples:

// Factorial function definition
fun fact:long (x:long) ->
    if x == 0 then
        1
    else
        let prev = fact (x - 1)
        x * prev

fact 5 // 120

// LINQ support
let squareSum = range 1 100
    |> Where (x -> x.even())
    |> Select (x -> x ** 2)
    |> Sum ()

// Pattern matching
fun desribe:string (arr:object[]) ->
    match arr with
        case [] then "empty array"
        case [x:int] when x < 10 then fmt "array with 1 small int ({0})" x
        case [x] then "array with 1 item"
        case [x; y] then "array with 2 items"
        case [x; y; ...z] then fmt "array with {0}, {1} and {2} more items" x y z.Length

For more information about the syntax, refer to specific Wiki pages (shown on the right).