let createToto() = 

    "toto service"

let createTiti() = 

    "titi service"

let createDefault() = 

    "default service"

​

let getService confloader =

    let conf = confloader()

    let f = match conf with

    | "toto" -> createToto

    | "titi" -> createTiti

    | _      -> createDefault

    f()

​

​

​

let confReader() = 

    "toto"

​

​

printfn "%s" (getService (confReader))