solidity link

pragma solidity ^0.5.0;

library LibSum {   
   function sumUsingInlineAssembly(uint[] memory _data) public pure returns (uint o_sum) {
      for (uint i = 0; i < _data.length; ++i) {
         assembly {
            o_sum := add(o_sum, mload(add(add(_data, 0x20), mul(i, 0x20))))
         }
      }
   }
}

pragma solidity ^0.5.0;
import './LibSum.sol';

contract TestSum {
   uint[] data;

   constructor() public {
      data.push(1);
      data.push(2);
      data.push(3);
      data.push(4);
      data.push(5);
   }
   function sum() external view returns(uint){      
      return LibSum.sumUsingInlineAssembly(data);
   }
}

const TestSum = artifacts.require("TestSum");
const LibSum = artifacts.require("LibSum");

module.exports = function (deployer) {
  deployer.deploy(LibSum);
  deployer.link(LibSum,TestSum);
  deployer.deploy(TestSum);
};