public static IArrow First <C>(this IArrow arr)
{
/*
* A slightly messy way of simplifying First using the IArrow interface and determining
* the types of the input arrow at runtime, so that it doesn't take three type
* parameters.
* Horrific code btw.
*/
Type a = arr.a;
Type b = arr.b;
Type c = typeof(C);
Type inputTupleType = typeof(Tuple <,>).MakeGenericType(a, c);
Type outputTupleType = typeof(Tuple <,>).MakeGenericType(b, c);
Type resultType = typeof(Arrow <,>).MakeGenericType(inputTupleType, outputTupleType);
Type funcType = typeof(Func <,>).MakeGenericType(inputTupleType, outputTupleType);
Type[] constructorTypes = new Type[1];
constructorTypes[0] = funcType;
ConstructorInfo constructor = resultType.GetConstructor(constructorTypes);
dynamic[] parameters = new dynamic[1];
parameters[0] = new Func <Tuple <dynamic, dynamic>, Tuple <dynamic, dynamic> >((Tuple <dynamic, dynamic> x) => new Tuple <dynamic, dynamic>(arr.Invoke(x.Item1), x.Item2));
return((IArrow)constructor.Invoke(parameters));
}