tuples

In C++0x, one can create a constexpr std::tuple, e.g. like #include <tuple> constexpr int i = 10; constexpr float f = 2.4f; constexpr double d = -10.4; constexpr std::tuple<int, float, double> tup(i, f, d); One also can query a std::tuple at runtime, e.g. via int i2 = std::get<0>(tup); But it is not possible to query it at compile time, e.g., constexpr int i2 = std::get<0>(tup); will throw a compilation error (at least with the latest g++ snapshot 2011-02-19). Is there any other way to query a constexpr std::tuple at compile time? And if not, is there a conceptual reason why one is not

I have a nested tuple structure like (String,(String,Double)) and I want to transform it to (String,String,Double) . I have various kinds of nested tuple, and I don't want to transform each manually. Is there any convenient way to do that? If you use shapeless , this is exactly what you need, I think. There is no flatten on a Tupple. But if you know the structure, you can do something like this: implicit def flatten1[A, B, C](t: ((A, B), C)): (A, B, C) = (t._1._1, t._1._2, t._2) implicit def flatten2[A, B, C](t: (A, (B, C))): (A, B, C) = (t._1, t._2._1, t._2._2) This will flatten Tupple with

Possible Duplicate: python: how to sort a complex list on two different keys I've got a list of tuples. I want to sort them depending two elements. Here is following example unsorted = [('a', 4, 2), ('a', 4, 3), ('a', 7, 2), ('a', 7, 3), ('b', 4, 2), ('b', 4, 3), ('b', 7, 2), ('b', 7, 3)] sorted = [('a', 4, 2), ('b', 4, 2), ('a', 4, 3), ('b', 4, 3), ('a', 7, 2), ('b', 7, 2), ('a', 7, 3), ('b', 7, 3)] I know how to sort them on the second element: sorted(unsorted, key = lambda element : element[1]) But how to do that with two keys? sorted(unsorted, key=lambda element: (element[1], element[2]))

I would like to access csv files in scala in a strongly typed manner. For example, as I read each line of the csv, it is automatically parsed and represented as a tuple with the appropriate types. I could specify the types beforehand in some sort of schema that is passed to the parser. Are there any libraries that exist for doing this? If not, how could I go about implementing this functionality on my own? product-collections appears to be a good fit for your requirements: scala> val data = CsvParser[String,Int,Double].parseFile("sample.csv") data: com.github.marklister.collections.immutable

In many places, (1,2,3) (a tuple) and [1,2,3] (a list) can be used interchangeably. When should I use one or the other, and why? From the Python FAQ : Lists and tuples, while similar in many respects, are generally used in fundamentally different ways. Tuples can be thought of as being similar to Pascal records or C structs; they're small collections of related data which may be of different types which are operated on as a group. For example, a Cartesian coordinate is appropriately represented as a tuple of two or three numbers. Lists, on the other hand, are more like arrays in other