public Dist <S> Select <S>(Func <T, S> selector)
{
return(Dist <T> .Map <S>(this, selector));
}
public Dist <R> SelectMany <S, R>(Func <T, Dist <S> > selector, Func <T, S, R> resultSelector)
{
return(Dist <T> .Bind(this, v => Dist <S> .Map(selector(v), u => resultSelector(v, u))));
}
private static Dist <S> Map <S>(Dist <T> distribution, Func <T, S> f)
{
return(new Dist <S>(distribution.values.Select(v => ProbValue <T> .Map(f, v))));
}
private static Dist <R> Join <S, R>(Dist <T> distribution1, Dist <S> distribution2, Func <T, S, R> f)
{
return(new Dist <R>(distribution1.SelectMany(v1 => distribution2.Select(v2 => v1.JoinWith(v2, f)))));
}
private static Dist <S> Bind <S>(Dist <T> distribution, Func <T, Dist <S> > f)
{
return(new Dist <S>(distribution.values.SelectMany(v => v.Probability * f(v.Value))));
}
public Dist <R> JoinWith <S, R>(Dist <S> distribution, Func <T, S, R> f)
{
return(Dist <T> .Join <S, R>(this, distribution, f));
}
public Dist <Tuple <T, S> > Prod <S>(Dist <S> distribution)
{
return(this.JoinWith(distribution, (v1, v2) => Tuple.Create <T, S>(v1, v2)));
}
/// <summary>
/// A point distribution.
/// </summary>
/// <typeparam name="T">The element type.</typeparam>
/// <param name="value">The value.</param>
/// <returns>A point distribution on the given value.</returns>
public static Dist <T> Certainly <T>(T value)
{
return(Dist <T> .Unit(value));
}
/// <summary>
/// Averages the specified distribution.
/// </summary>
/// <param name="distribution">The distribution.</param>
/// <returns>The expected value for the given distribution.</returns>
public static decimal Average(this Dist <decimal> distribution)
{
return(distribution.Average(v => v));
}