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  1. using System;
  2.  
  3. public class Option {
  4. 	public static Option<T> None<T>() {
  5. 		return new Option<T>(default(T), present: false);
  6. 	}
  7.  
  8. 	public static Option<T> Some<T>(T value) {
  9. 		return new Option<T>(value, present: true);
  10. 	}
  11. }
  12.  
  13. public class Option<T> {
  14. 	private readonly T value;
  15. 	public bool Present { get; private set; }
  16.  
  17. 	internal Option(T value, bool present) {
  18. 		this.value = value;
  19. 		Present = present;
  20. 	}
  21.  
  22. 	public T Get() {
  23. 		if (!Present) {
  24. 			throw new Exception("you suck");
  25. 		}
  26. 		return value;
  27. 	}
  28.  
  29. 	public Option<U> Select<U>(Func<T, U> f) {
  30. 		if (Present) {
  31. 			return Option.Some<U>(f(value));
  32. 		} else {
  33. 			return Option.None<U>();
  34. 		}
  35. 	}
  36.  
  37. 	public override string ToString() {
  38. 		if (Present) {
  39. 			return "Some(" + value.ToString() + ")";
  40. 		} else {
  41. 			return "None";
  42. 		}
  43. 	}
  44. }
  45.  
  46. public static class Program {
  47. 	public static void Main() {
  48. 		Console.WriteLine(Option.Some("hello").Select(x => x.Length));
  49. 		Console.WriteLine(Option.None<string>().Select(x => x.Length));
  50. 	}
  51. }
Success #stdin #stdout 0.03s 33880KB
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https://ideone.com/Bh5fvi
language:
C# (gmcs 5.20.1)
created:
9 years ago
visibility:
public

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