Application libraries are the most commonly used implementation approach to solve problems in general-purpose languages. Their competitors are domain-specific languages, which can provide notation close to the problem domain. We carried out an empirical study on comparing domain-specific languages and application libraries regarding program understanding. In this paper, one case study is presented. Over 3000 lines of code were studied and more than 86 pages long questionnaires were answered by end-users, answering questions on learning, perceiving and evolving programs written in domain-specific language as well as general-purpose language using application library. In this paper, we present comparison results on end-users' correctness and consumed time. For domain-specific language and application library same problem domain has been used—a well-known open source graph description language, DOT.