Often, people such as educators, artists, and researchers wish to quickly generate robot motion. However, current toolchains for programming robots can be difficult to learn, especially for people without technical training. This paper presents the Improv system, a programming language for high-level description of robot motion with immediate visualization of the resulting motion on a physical or simulated robot. Improv includes a "live coding" wrapper for ROS ("Robot Operating System", an open-source robot software framework which is widely used in academia and industry, and integrated with many commercially available robots). Commands in Improv are compiled to ROS messages. The language is inspired by choreographic techniques, and allows the user to compose and transform movements in space and time. In this paper, we present our work on Improv so far, as well as the design decisions made throughout its creation.