在F#中实现IList<T>和IReadOnlyList<T>

type MyList<'T>() =
    let mutable items : 'T list = []

    interface System.Collections.Generic.IList<'T> with
        member this.Add(item) = items <- items @ [item]
        member this.Clear() = items <- []
        member this.Contains(item) = List.contains item items
        member this.CopyTo(array, arrayIndex) = items |> List.toArray |> Array.copyTo(array, arrayIndex)
        member this.Count = List.length items
        member this.GetEnumerator() = items.GetEnumerator()
        member this.IndexOf(item) = List.findIndex ((=) item) items
        member this.Insert(index, item) = items <- List.insert index item items
        member this.IsReadOnly = false
        member this.Item
            with get(index) = List.item index items
            and set(index, value) = items <- List.setAt index value items
        member this.Remove(item) = items <- List.filter ((<>) item) items
        member this.RemoveAt(index) = items <- List.removeAt index items

    interface System.Collections.Generic.IReadOnlyList<'T> with
        member this.Item with get(index) = List.item index items

let myList = MyList<int>()
myList.Add(1)
myList.Add(2)
myList.Add(3)

printfn "Count: %d" myList.Count
printfn "Item at index 1: %d" myList.[1]

let myList : IList<int> = [1; 2; 3]
let myReadOnlyList : IReadOnlyList<int> = [1; 2; 3]

printfn "Count: %d" myList.Count
printfn "Item at index 1: %d" myList.[1]