Aliasing in C#

alias.cs

public abstract class Alias
{
    protected readonly string Value;

    protected Alias(string value)
    {
        if (value == null) throw new ArgumentNullException("value");
        if (string.Empty.Equals(value, StringComparison.InvariantCultureIgnoreCase))
            throw new ArgumentException("Value must not be empty.", "value");
        Value = value;
    }

    public static implicit operator string(Alias alias)
    {
        return alias.Value;
    }


    public override string ToString()
    {
        return Value;
    }
}

example_impl.cs

public class Sql : Alias
{
    public Sql(string sql) : base(sql)
    {}

    public static implicit operator Sql(string sql)
    {
        return new Sql(sql);
    }
}

explain.md

Why?

1. In particular when using Func or similar types it can be hard to communicate the meaning. Creating an aliased type like this can provide a much stronger semantic.
2. Similar to 1, in methods that return simple types, such as strings, it provides a stronger semantic to the signature if the type returned informs about the 'type' of string, rather than the simple fact of it being a string
3. Similar, but when creating dictionary types, if the key is a string, what is special about it?
4. Because I miss this capability in languages such as F# and Haskell (not that this is as good)