A structured approach to retrieving functions by types

Abstract

Functional programming supports the idea of reusing existing diction components to build a new fQnction component through features such as higher-order functions and parametric polymorphic functions. Retrieving fhnctions is an important process for function reuse. This poster addresses the problem of diction retrieval using types and of organizing the function library.There have been proposed methods of searching for fonctions by using types of the dictions as search keys [ 1,2,3, 4, 51. Runciman and Toyn [4] presented a method of retrieving a function using the type of the function implicitly formulated from the contexts. In [2, 31 Rittri described type-based retrieval methods in which the type of the desired fimction is explicitly formulated and the argument order of the desired function does not have to be provided by the user. Zarcmski and Wing [S] extended the retrieval by types to modules and to a variety of matches. All the above methods deal with the retrieval problem from an unstructured library. In [l] Park and Ramjisingh presented a method of structuring function components in a reuse library based on potential reusability among functions, and described a type-based retrieval method from the hierarchically structured library. Two kinds of reusability among l5nctions were considered: reuse by type substitution and by argument substitution. The retrieval is more efficient thau the unstructured library baaed retrieval. The user can also browse the structured library via the reusability links as an aid in finding reusable functions. However the user specifies the order of arguments of the desired function.In this poster we propose a method of structuring a function library aud an efficient type-based retrieval method based on the structured library. In searching for functions, the argument order of the diction needs not have to be given by the user as in [2, 31. Our method is based on an extended notion of regular types called set types in order to capture all the functions of the same type by ignoring the order of arguments. For example, an extended set type {list(inr), int) -> list(inr) contains the types list(int)-> int -> list(int) and int->list(inr)->list(int).Suppose that the user wants to retrieve fitnctions with two arguments (the argument order is not important) such that the type of one of the argument is fist(int) and the other argument's type is int, and the retum type is list(int). The user provides flist(int), int) -> list(int) (or equally {int, list(ingj -> list(int)) as the type of the desired function.