+ StructuredFormatDisplay to NonEmptyList

src/FSharpPlus/Data/NonEmptyList.fs

@@ -8,13 +8,16 @@
 
 
 /// A type-safe list that contains at least one element.
+[<StructuredFormatDisplay("{StructuredFormatDisplay}")>]
 type NonEmptyList<'t> = {Head: 't; Tail: 't list} with
     interface IEnumerable<'t> with member x.GetEnumerator () = (let {Head = x; Tail = xs} = x in seq (x::xs)).GetEnumerator ()
     interface System.Collections.IEnumerable with member x.GetEnumerator () = (let {Head = x; Tail = xs} = x in seq (x::xs)).GetEnumerator () :> System.Collections.IEnumerator
     interface IReadOnlyCollection<'t>        with member s.Count = 1 + List.length s.Tail
     interface IReadOnlyList<'t>              with member s.Item with get index = s.Item index
     interface NonEmptySeq<'t>                with member s.First = s.Head
 
+    member private this.StructuredFormatDisplay = "nelist {" + (sprintf "%A" (this.Head::this.Tail)).[1..^1] + "}"
+
     [<System.Obsolete("Use Head instead.")>]
     member this.head = let {Head = a; Tail = _} = this in a