ECLAIR is a Prolog-based prototype system aiming to provide a functionally complete environment for the study, development and evaluation of programming language analysis and implementation tools. In this paper, we sketch the overall structure of the system, outlining the main methodologies and technologies underlying its components. We also discuss the appropriateness of Prolog as the implementation language for the system: besides highlighting its strengths, we also point out a few potential weaknesses, hinting at possible solutions.