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  1. open System.Collections.Generic
  2.  
  3. type IDictionary<'TKey, 'TValue> with
  4.     member this.GetOrAdd (key:'TKey, fun':'TKey -> 'TValue) =
  5.         match this.ContainsKey key with
  6.           | true  -> this.Item key
  7.           | false -> let val' = fun' key
  8.                      this.Add (key, val')
  9.                      val'
  10.  
  11. let dd =
  12.     let d = Dictionary()
  13.     d.Add (1, 2)
  14.     d.Add (3, 4)
  15.     d
  16.  
  17. printfn "%A" dd
  18. dd.GetOrAdd (5, (fun x -> 2 * x)) |> printfn "%A :: %d" dd
  19. dd.GetOrAdd (5, (fun x -> 9 * x)) |> printfn "%A :: %d" dd
  20.  
Success #stdin #stdout 0.22s 25360KB
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seq [[1, 2]; [3, 4]]
seq [[1, 2]; [3, 4]; [5, 10]] :: 10
seq [[1, 2]; [3, 4]; [5, 10]] :: 10
https://ideone.com/z7NFm8
language:
F# (mono 4.1)
created:
9 years ago
visibility:
public

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