Contracts in Nemerle

gistfile1.n

class Person
{
    public Name: string;
            
    public this(name: string)
    requires name != null
    {
        Name = name;
    }
}

// causes nice "Nemerle.Core.AssertionException: assertion ``name != null'' 
// failed in file Main.n, line 105: The ``Requires'' contract of method `.ctor' has been violated."
def person = Person(null);