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21
A Polymorphic Record Calculus and Its Compilation
 ACM Transactions on Programming Languages and Systems
, 1995
"... this article appeared in Proceedings of ACM Symposium on Principles of Programming Languages, 1992, under the title \A compilation method for MLstyle polymorphic record calculi." This work was partly supported by the Japanese Ministry of Education under scienti c research grant no. 06680319. Author ..."
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Cited by 72 (8 self)
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this article appeared in Proceedings of ACM Symposium on Principles of Programming Languages, 1992, under the title \A compilation method for MLstyle polymorphic record calculi." This work was partly supported by the Japanese Ministry of Education under scienti c research grant no. 06680319. Author's address: Research Institute for Mathematical Sciences, Kyoto University, Sakyoku, Kyoto 60601, JAPAN; email: ohori@kurims.kyotou.ac.jp Permission to copy without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of ACM. To copy otherwise, or to republish, requires a fee and/or speci c permission. c 1999 ACM 01640925/99/01000111 $00.75
From Polyvariant Flow Information to Intersection and Union Types
 J. FUNCT. PROGRAMMING
, 1998
"... Many polyvariant program analyses have been studied in the 1990s, including kCFA, polymorphic splitting, and the cartesian product algorithm. The idea of polyvariance is to analyze functions more than once and thereby obtain better precision for each call site. In this paper we present an equivalen ..."
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Cited by 41 (7 self)
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Many polyvariant program analyses have been studied in the 1990s, including kCFA, polymorphic splitting, and the cartesian product algorithm. The idea of polyvariance is to analyze functions more than once and thereby obtain better precision for each call site. In this paper we present an equivalence theorem which relates a coinductively defined family of polyvariant ow analyses and a standard type system. The proof embodies a way of understanding polyvariant flow information in terms of union and intersection types, and, conversely, a way of understanding union and intersection types in terms of polyvariant flow information. We use the theorem as basis for a new flowtype system in the spirit of the CIL calculus of Wells, Dimock, Muller, and Turbak, in which types are annotated with flow information. A flowtype system is useful as an interface between a owanalysis algorithm and a program optimizer. Derived systematically via our equivalence theorem, our flowtype system should be a g...
Polymorphism and Type Inference in Database Programming
"... In order to find a static type system that adequately supports database languages, we need to express the most general type of a program that involves database operations. This can be achieved through an extension to the type system of ML that captures the polymorphic nature of field selection, toge ..."
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Cited by 38 (10 self)
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In order to find a static type system that adequately supports database languages, we need to express the most general type of a program that involves database operations. This can be achieved through an extension to the type system of ML that captures the polymorphic nature of field selection, together with a technique that generalizes relational operators to arbitrary data structures. The combination provides a statically typed language in which generalized relational databases may be cleanly represented as typed structures. As in ML types are inferred, which relieves the programmer of making the type assertions that may be required in a complex database environment. These extensions may also be used to provide static polymorphic typechecking in objectoriented languages and databases. A problem that arises with objectoriented databases is the apparent need for dynamic typechecking when dealing with queries on heterogeneous collections of objects. An extension of the type system needed for generalized relational operations can also be used for manipulating collections of dynamically typed values in a statically typed language. A prototype language based on these ideas has been implemented. While it lacks a proper treatment of persistent data, it demonstrates that a wide variety of database structures can be cleanly represented in a polymorphic programming language.
Generalizing Generalized Tries
, 1999
"... A trie is a search tree scheme that employs the structure of search keys to organize information. Tries were originally devised as a means to represent a collection of records indexed by strings over a fixed alphabet. Based on work by C.P. Wadsworth and others, R.H. Connelly and F.L. Morris generali ..."
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Cited by 31 (8 self)
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A trie is a search tree scheme that employs the structure of search keys to organize information. Tries were originally devised as a means to represent a collection of records indexed by strings over a fixed alphabet. Based on work by C.P. Wadsworth and others, R.H. Connelly and F.L. Morris generalized the concept to permit indexing by elements of an arbitrary monomorphic datatype. Here we go one step further and define tries and operations on tries generically for arbitrary firstorder polymorphic datatypes. The derivation is based on techniques recently developed in the context of polytypic programming. It is well known that for the implementation of generalized tries nested datatypes and polymorphic recursion are needed. Implementing tries for polymorphic datatypes places even greater demands on the type system: it requires rank2 type signatures and higherorder polymorphic nested datatypes. Despite these requirements the definition of generalized tries for polymorphic datatypes is...
Static type inference for parametric classes
 In Proceedings of ACM OOPSLA conference
, 1989
"... Method inheritance and data abstraction are central features of objectoriented programming that are attained through a hierarchical organization of classes. Recent studies have shown that method inheritance can be supported by an ML style type inference when extended to labeled records. This is bas ..."
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Cited by 24 (5 self)
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Method inheritance and data abstraction are central features of objectoriented programming that are attained through a hierarchical organization of classes. Recent studies have shown that method inheritance can be supported by an ML style type inference when extended to labeled records. This is based on the observation that a function that selects a field f of a record can be given a polymorphic type that enables it to be applied to any record which contains a field f. Several type systems also provide data abstraction through abstract type declarations. However, these two features have not yet been properly integrated in a statically checked polymorphic type system. This paper proposes a static type system that achieves this integration in an MLlike polymorphic language by adding a class construct which allows the programmer to build a hierarchy of classes connected by multiple inheritance declarations. Classes can be parameterized by types allowing “generic ” definitions. The type correctness of class declarations is statically checked, and a principal scheme is inferred for any type correct program containing methods and objects defined in classes. Moreover, the type system can be extended to include the structures and operations needed for database programming and therefore can serve as a basis of an objectoriented database programming language. 1
Query efficient implementation of graphs of bounded clique width
 Discrete Applied Mathematics
, 2003
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On the theory of structural subtyping
, 2003
"... We show that the firstorder theory of structural subtyping of nonrecursive types is decidable. Let Σ be a language consisting of function symbols (representing type constructors) and C a decidable structure in the relational language L containing a binary relation ≤. C represents primitive types; ..."
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Cited by 18 (8 self)
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We show that the firstorder theory of structural subtyping of nonrecursive types is decidable. Let Σ be a language consisting of function symbols (representing type constructors) and C a decidable structure in the relational language L containing a binary relation ≤. C represents primitive types; ≤ represents a subtype ordering. We introduce the notion of Σtermpower of C, which generalizes the structure arising in structural subtyping. The domain of the Σtermpower of C is the set of Σterms over the set of elements of C. We show that the decidability of the firstorder theory of C implies the decidability of the firstorder theory of the Σtermpower of C. This result implies the decidability of the firstorder theory of structural subtyping of nonrecursive types.
On Proving Left Termination of Constraint Logic Programs
 ACM Transaction on Computational Logic
, 2001
"... The Constraint Logic Programming (CLP) Scheme merges logic programming with constraint solving over predefined domains. In this paper, we study proof methods for universal left termination of constraint logic programs. We provide a sound and complete characterization of left termination for ideal CL ..."
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Cited by 17 (7 self)
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The Constraint Logic Programming (CLP) Scheme merges logic programming with constraint solving over predefined domains. In this paper, we study proof methods for universal left termination of constraint logic programs. We provide a sound and complete characterization of left termination for ideal CLP languages which generalizes acceptability of logic programs. The characterization is then refined to the notion of partial acceptability, which is wellsuited for automatic modular inference. We describe a theoretical framework for automation of the approach, which is implemented. For nonideal CLP languages and without any assumption on their incomplete constraint solvers, even the most basic sound termination criterion from logic programming does not lift. We focus on a specific system, namely CLP(R), by proposing some additional conditions that make (partial) acceptability sound
Polytypic Programming With Ease
, 1999
"... A functional polytypic program is one that is parameterised by datatype. Since polytypic functions are defined by induction on types rather than by induction on values they typically operate on a higher level of abstraction than their monotypic counterparts. However, polytypic programming is not nec ..."
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Cited by 13 (5 self)
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A functional polytypic program is one that is parameterised by datatype. Since polytypic functions are defined by induction on types rather than by induction on values they typically operate on a higher level of abstraction than their monotypic counterparts. However, polytypic programming is not necessarily more complicated than conventional programming. We show that a polytypic function is uniquely defined by its action on constant functors, projection functors, sums, and products. This information is sufficient to specialize a polytypic function to arbitrary polymorphic datatypes, including mutually recursive datatypes and nested datatypes. The key idea is to use infinite trees as index sets for polytypic functions and to interpret datatypes as algebraic trees. This approach appears both to be simpler, more general, and more efficient than previous ones which are based on the initial algebra semantics of datatypes. Polytypic functions enjoy polytypic properties. We show that wellkno...
Efficient and Flexible Matching of Recursive Types
, 2000
"... Equality and subtyping of recursive types have been studied in the 1990s by Amadio and Cardelli; Kozen, Palsberg, and Schwartzbach; Brandt and Henglein; and others. Potential applications include automatic generation of bridge code for multilanguage systems and typebased retrieval of software m ..."
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Cited by 9 (3 self)
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Equality and subtyping of recursive types have been studied in the 1990s by Amadio and Cardelli; Kozen, Palsberg, and Schwartzbach; Brandt and Henglein; and others. Potential applications include automatic generation of bridge code for multilanguage systems and typebased retrieval of software modules from libraries. Auerbach, Barton, and Raghavachari advocate a highly exible combination of matching rules for which there, until now, are no ecient algorithmic techniques. In this paper, we present an ecient decision procedure for a notion of type equality that includes unfolding of recursive types, and associativity and commutativity of product types, as advocated by Auerbach et al. For two types of size at most n, our algorithm decides equality in O(n 2 ) time. The algorithm iteratively prunes a set of type pairs, and eventually it produces a set of pairs of equal types. In each iteration, the algorithm exploits a socalled coherence property of the set of type pairs pr...