I just learned that there is an equivalent in F# to the using statement in C# and VB.NET. There are actually two approaches; one a using function that is passed a function or lambda and the second is a binding similar to the let statement except that it also acts as a using statement when the value goes out of scope. The docs do a good job explaining it. Here is a little demo of the two approaches:

#light

open System
open System.IO

let readFile path = 
    use r = new StreamReader(new FileStream(path, FileMode.Open))
    Console.WriteLine(r.ReadToEnd())

let readFile2 path = 
    using (new StreamReader(new FileStream(path, FileMode.Open)))  
        (fun r -> Console.WriteLine(r.ReadToEnd()))

readFile @"D:\temp\test.txt"
readFile2 @"D:\temp\test.txt"

Console.ReadKey() |> ignore