Sum vector elements homorphically I'm looking for the homomorphic version of the following (I'm using Python here):

$ a = [1,2,3]
$ s = sum(a)  
$ print(s)
6


Is there an open source fully homomorphic library which is able to do $sum(vector)$? So far I just found libraries allowing operations with input-output either only vectorial or only integer. Here I'm asking for a vector to integer operation.

Of course there is another way, namely encrypting every integer element of $a$ individually, summing in the encrypted domain, and then decrypt the result. Since I would like to take advantage of the speed of vector batching, I'm not considering this as a good solution.
As far as I know, there are many libraries that use lattices and LWE schemes to implement fully homomorphic Encryptions.

This is a set, Most of them is in C++ and Only one by MSFT is C#, But in all cases you can port the code to python aftor compiling:


HElib in C++
SEAL By MicroSoft C++/C#
Palisade C++
FHEW C/C++
TFHE C++
NFLib C++


Note: The set in no particular order.