ImmutableStack in F# Part 2
I'm a bit busier than I thought I would be after returning from vacation. But I had a little bit of time to play around with the implementation again today. Thanks to all the suggestions in the comments from the previous post.
This version has a couple of improvements including
- Removing the ambiguous constructor
- More efficient All() implementation
Remaining issues:
- Need to make it generic :)
- Still exposing a type union. Great for F# but it produces somewhat awkward looking metadata for non-F# languages to consume
#light
namespace Col
type ImmutableStack =
| EmptyStack
| Value of int * ImmutableStack
static member Empty = EmptyStack
static member Create( l:#seq<int> ) =
let s = ref ImmutableStack.Empty
l |> Seq.iter (fun n -> s := (!s).Push(n) )
!s
member x.Count =
let rec count t (cur:ImmutableStack) =
match cur.IsEmpty with
| true -> t
| false -> count (t+1) (cur.Pop())
count 0 x
member x.IsEmpty =
match x with
| EmptyStack -> true
| _ -> false
member x.Push(y) = Value(y,x)
member x.Peek() =
match x with
| EmptyStack -> failwith "ImmutableStack is empty"
| Value (v,_) -> v
member x.Pop() =
match x with
| EmptyStack -> failwith "ImmutableStack is empty"
| Value (_,n) -> n
member x.Reverse() =
let rec doBuild (cur:ImmutableStack) (building:ImmutableStack) =
match cur.IsEmpty with
| true -> building
| false -> doBuild (cur.Pop()) (building.Push(cur.Peek()))
doBuild x ImmutableStack.Empty
member x.All() =
match x with
| EmptyStack-> Seq.empty<int>
| Value (v,n) -> seq {
yield v
yield! n.All() }