type StructId = Int

struct_id_builder :: [StructId] -> IO Tree StructId struct_id_builder = récupère et construit l'arbre des struct_id dans HAL

struct_id_clean :: Tree StructId -> Tree StructId struct_id_clean = enlève les doublons

struct_id_lookup :: StructId -> Tree StructId -> Tree StructId struct_id_flat :: Tree StructId -> [StructId]

note pour plus tard: struct_id_merge :: Tree StructId -> Tree StructId -> Tree (Maybe StructId, Maybe StructId)

struct_id_diff : filter where fst and snd différents et au moins l'un isJust