this is code from my camera class. It's openfl but I believe the functions basically either change in place or return a new vector in the same ways in openfl and lime:

case FORWARD:
                var tgt = cameraFront.clone();
                tgt.scaleBy(speed);
                cameraPos = cameraPos.add(tgt);
            case BACKWARD:
                var tgt = cameraFront.clone();
                tgt.scaleBy(speed);
                cameraPos = cameraPos.subtract(tgt);
            case RIGHT:
                var m = cameraFront.crossProduct(_worldUp);
                m.normalize();
                m.scaleBy(speed);
                cameraPos = cameraPos.subtract(m);
            case LEFT:
                var m = cameraFront.crossProduct(_worldUp);
                m.normalize();
                m.scaleBy(speed);
                cameraPos = cameraPos.add(m);