Mutual recursion with computation expressions

Question

Currently I have the following structure:

let rec foo x = State.state{
    let rec bar =
        //...
        foo 5
        //...
    //...
    bar
    //...
}

I would like to extract the 'bar' function and obtain a structure such as:

let rec foo x = State.state{
    //...
    bar
    //...
}
and bar =  State.state{
    //...
    foo 5
    //...
}

This would allow me to have another function foo2 that could also use bar and avoid code duplication.

The question is: my proposal does not compile in F# and apparently that is because of the State context. So what is the syntactically correct way to reach the desired code structure?

Answer 1

This works fine for me:

let rec foo x = 
  async {
    return! bar x
  }
and bar x = 
  async {
    if x = 0
      then printfn "bar"
      else do! foo (x - 1) 
  }
Async.RunSynchronously (foo 10)

I had problems with the formatting first so make sure your indentations are correct and that your exclamation marks are at the right place, otherwise the type won't work out.