function to Visualizing Data in a Grid in F#

I wrote the following function to view data in a grid from F# interactive:

open System.Windows.Forms
let grid x = 
   let form = new Form(Visible = true)
   let data = new DataGridView(Dock = DockStyle.Fill)
   form.Controls.Add(data)
   data.DataSource <- x |> Seq.toArray

How can I make it work开发者_JAVA技巧 for both 1D and 2D seqs? say, grid [1,2,3] or grid[(1,0);(2,0);(3,0)];; works fine but grid [1;2;3];; would not work.

another question is, why do I have to add the `|>Seq.toArray to make it work?

DataGridView uses databinding that reflects over object properties and displays them in grid columns (possibly automatically inferred). [1,2,3] and [(1,0);(2,0);(3,0)] are lists of tuples so DataGridView can show tuple components, As opposite, [1;2;3] - list of integers, it doesn't contains any properties that exposes the actual value.

Seq.ToArray is necessary because DataSource expects IList, IListSource, IBindingList or IBindingListView (DataGridView.DataSource Property ). Array implements IList, F# list - doesn't.

As desco explains, the DataGridView control displays values of properties of the object.

This is pretty silly behavior for primitive types - for example if you specify [ "Hello"; "world!" ] as the data source, it will display column Length with values 5 and 6. That's definitely not what you'd want!

The best solution I could find is to explicitly check for strings and primitive types and wrap them in a simple type with just a single property (that will get displayed):

type Wrapper(s:obj) = 
  member x.Value = s.ToString()

let grid<'T> (x:seq<'T>) =     
  let form = new Form(Visible = true)    
  let data = new DataGridView(Dock = DockStyle.Fill)    
  form.Controls.Add(data)    
  data.AutoGenerateColumns <- true
  if typeof<'T>.IsPrimitive || typeof<'T> = typeof<string> then
    data.DataSource <- [| for v in x -> Wrapper(box v) |]
  else 
    data.DataSource <- x |> Seq.toArray

grid [ 1 .. 10 ]
grid [ "Hello"; "World" ]