Created
September 26, 2016 09:08
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| public class Result<T> | |
| { | |
| public bool HasException { get; } | |
| public Exception Exception { get; } | |
| public T Value { get; } | |
| public Result(T value) | |
| { | |
| HasException = false; | |
| Value = value; | |
| } | |
| public Result(Exception exception) | |
| { | |
| HasException = true; | |
| Exception = exception; | |
| } | |
| public Result(Func<T> getValue) | |
| { | |
| try | |
| { | |
| Value = getValue(); | |
| HasException = false; | |
| } | |
| catch (Exception exc) | |
| { | |
| Exception = exc; | |
| HasException = true; | |
| } | |
| } | |
| public override string ToString() | |
| => HasException ? Exception.GetType().Name : (Value != null ? Value.ToString() : "null"); | |
| } | |
| public static class Result | |
| { | |
| public static Result<T> From<T>(T value) | |
| { | |
| return value.Unit(); | |
| } | |
| public static Result<T> Execute<U0, T>(Func<U0, T> fn, U0 u0) | |
| { | |
| return Execute(() => fn(u0)); | |
| } | |
| public static Result<T> Execute<T>(Func<T> getValue) | |
| { | |
| return getValue.Unit(); | |
| } | |
| } | |
| public static class ResultMonadExtensions | |
| { | |
| public static Result<T> Unit<T>(this T value) | |
| { | |
| return new Result<T>(value); | |
| } | |
| public static Result<T> Unit<T>(this Func<T> getValue) | |
| { | |
| return new Result<T>(getValue); | |
| } | |
| public static Result<TU> Bind<T, TU>(this Result<T> value, Func<T, Result<TU>> k) | |
| { | |
| return (value.HasException) | |
| ? new Result<TU>(value.Exception) | |
| : k(value.Value); | |
| } | |
| } | |
| public static class ResultExtensions | |
| { | |
| public static Result<T2> Then<T, T2>(this Result<T> value, Func<T, T2> getValue) | |
| { | |
| return value.Bind(x => Result.Execute(() => getValue(x))); | |
| } | |
| public static Result<T> ThenEnsure<T>(this Result<T> value, Func<T, bool> validate) | |
| { | |
| if (value.HasException) | |
| return new Result<T>(value.Exception); | |
| return validate(value.Value) | |
| ? new Result<T>(value.Value) | |
| : new Result<T>(new ValidationException($"Validation failed on {validate.Method.Name}", nameof(value))); | |
| } | |
| public static Result<T2> ThenEither<T, T2>(this Result<T> value, Func<T, bool> conditional, Func<Result<T>, Result<T2>> onTrue, Func<Result<T>, Result<T2>> onFalse) | |
| { | |
| try { | |
| var isTrue = conditional(value.Value); | |
| return value.Bind(x => isTrue ? onTrue(value) : onFalse(value)); | |
| } | |
| catch(Exception e) | |
| { | |
| return new Result<T2>(e); | |
| } | |
| } | |
| } |
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