+ StructuredFormatDisplay to NonEmptyList

src/FSharpPlus/Data/NonEmptyList.fs

@@ -8,13 +8,20 @@ open FSharpPlus.Control
 
 
 /// A type-safe list that contains at least one element.
+#if !FABLE_COMPILER
+[<StructuredFormatDisplay("{StructuredFormatDisplay}")>]
+#endif
 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
 
+#if !FABLE_COMPILER
+    member private this.StructuredFormatDisplay = "nelist {" + (sprintf "%A" (this.Head::this.Tail)).[1..^1] + "}"
+#endif
+
     member this.Item = function 0 -> this.Head | n -> this.Tail.[n-1]
     member this.GetSlice = function
         | None  , None