Turtles dojo

The goal of this dojo is to create a simple version of the Turtle/Logo language, using F# discriminated unions, to produce SVG graphics like this one:

... which is generated from the following code:

[
REPEAT (
    50, 
    (
    [
        FORWARD 10.0
        LEFT 10.
        REPEAT (5,
            [
                FORWARD 50.
                LEFT 140.
            ]
        )
    ]
))
]

Running the code