When it comes to finding functions in libraries, in whichever language, programmers struggle with the need for efficient tools able to retrieve all relevant functions in a reasonable time. For the OCaml language, dowsindex was developed to offer a solution to this problem, via the notion of isomorphisms of types. It relies on the construction of an Index to precompute information on the libraries and thus facilitate the search algorithm. We aim to improve its performances by proposing a new data structure representing the matching relation between types, along with a new heuristic to optimize the type search.