Some fiddling around with FSharp

Capstone1.fs

open System
let petrolOfCar = 100
type Destination = Home | Office | Stadium | GasStation

let driveTo destination currentPetrol =
    let remainingPetrol =
        match destination with
        | Home -> currentPetrol - 25
        | Office -> currentPetrol - 50
        | Stadium -> currentPetrol - 25
        | GasStation -> (currentPetrol - 10) + 50
    match remainingPetrol with
        | belowZero when belowZero < 0 -> failwith "Not enough petrol"
        | _ -> remainingPetrol

let lowerCase (x: string) = x.ToLower()

let rec getDestination() =
    let input = Console.ReadLine() |> lowerCase
    match input with
    | "home" -> Destination.Home
    | "office" -> Destination.Office
    | "stadium" -> Destination.Stadium
    | "gas station" -> Destination.GasStation
    | _ -> getDestination()

let main petrolOfCar =
    let mainInner petrol =
        try
            let destination = getDestination()
            printfn "Trying to drive to %A" destination
            let petrolLeft = driveTo destination petrol
            printfn "Made it to %A! You have %i petrol left" destination petrolLeft
            petrolLeft
        with ex ->
            printfn "ERROR: %s" ex.Message
            petrol
    petrolOfCar |> Seq.unfold (fun petrolLeft -> Some(petrolLeft, petrolLeft |> mainInner))

for x in main petrolOfCar do ignore x