> regarding "box" vs. "block". Other languages > (C# is the only one that comes to mind off-hand)

F# actually uses box much like Rust does:

    // box an int
    let o = box 1

Examples: http://fsharpforfunandprofit.com/posts/cli-types/

MSDN: https://msdn.microsoft.com/en-us/library/ee340516.aspx