Christoph Beierle and Gregor Meyer. Run-time type computations in the Warren abstract machine. Journal of Logic Programming, 18:123--148, 1994.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....serve not only for Prolog proper, but also for constructing compilers for related languages. To list just a few examples, abstract machine techniques were used for a parallel Prolog compiler ( 19] for variants of Prolog that use di#erent resolution methods ( 43] extend Prolog with types ([6]) or with record structures ( 42] and for a general theorem prover ( 37] There have even been attempts to construct a methodology for the design of abstract machines for logic programming languages ( 26, 29] A similar approach was applied to LIFE ( 3] which is a general purpose logic ....

Christoph Beierle and Gregor Meyer. Run-time type computations in the Warren abstract machine. Journal of Logic Programming, 18:123--148, 1994.

....of solutions. In this paper we describe the implementation of a functional logic language with subtyping whose operational semantics is based on typed lazy narrowing (other implementations of typed logic languages are [19] based on Prolog, and [5] based on a WAM extension with typed unification [6]) Typed lazy narrowing was presented in [1] and defines a rewriting calculus for solving data and type constraints, but it does not state any concrete strategy for combining these solvings. The interest of this combination is the use of type constraints for pruning the search space of data ....

C. Beierle, G. Meyer. Run-Time Type Computations in the Warren Abstract Machine, JLP, 18, pp. 123-148, 1994.

....speci cations [30] Related with these works, 35] has presented a simple type system for a typed logic framework in which programs are evaluated by means of a SLDNF resolution based 3 evaluation mechanism. Other authors have been working in the de nition of a Warren style abstract machine [11, 10], which bases the implementation of the language PROTOS L [13] and in which interesting applications have been written. Finally, as in the functional paradigm case, type inference for logic programming has been covered, as a part of the works [55, 35] and in [12] The aim of the present paper is ....

C. Beierle and G. Meyer. Run-time type computations in the warren abstract machine. The Journal of Logic Programming, 18(2):123-148, 1994. 62

....serve not only for Prolog proper, but also for constructing compilers for related languages. To list just a few examples, abstract machine techniques were used for a parallel Prolog compiler ( 19] for variants of Prolog that use di erent resolution methods ( 43] extend Prolog with types ([6]) or with record structures ( 42] and for a general theorem prover ( 37] There have even been attempts to construct a methodology for the design of abstract machines for logic programming languages ( 26, 29] A similar approach was applied to LIFE ( 3] which is a general purpose logic ....

Christoph Beierle and Gregor Meyer. Run-time type computations in the Warren abstract machine. Journal of Logic Programming, 18:123-148, 1994.

....with parametric order sorted types. In this paper we describe the implementation of a functional logic language with subtyping. Previous implementations of typed logic languages present Prolog implementations (language TEL [Smo88] or describe WAM extensions, so called PAM abstract machine [BeMe94, BeBo96], with typed unification (language PROTOS L [Bei95b] Typed lazy narrowing presented in [AG97] defines a rewriting calculus for solving data constraints and type constraints, but it does not state any concrete strategy in which they should be combined. The interest of an strategy of combined data ....

C. Beierle, G. Meyer. Run-Time Type Computations in the Warren Abstract Machine, JLP, 18, pp. 123-148, 1994.

....serve not only for Prolog proper, but also for constructing compilers for related languages. To list just a few examples, abstract machine techniques were used for a parallel Prolog compiler ( 19] for variants of Prolog that use different resolution methods ( 43] extend Prolog with types ([6]) or with record structures ( 42] and for a general theorem prover ( 37] There have even been attempts to construct a methodology for the design of abstract machines for logic programming languages ( 26, 29] A similar approach was applied to LIFE ( 3] which is a general purpose logic ....

Christoph Beierle and Gregor Meyer. Run-time type computations in the Warren abstract machine. Journal of Logic Programming, 18:123--148, 1994.

....for an overview see [11] In this paper we consider polymorphic types combined with order sorted types, i.e. types which are hierarchically ordered. Polymorphism for logic programming was first suggested in [10] for extensions of this approach to order sorted types see [4] 6] 13] 8] [3]. In all of these approaches, a precondition for the well definedness of the semantics of a typed logic program is that the program is well typed. Thus, static) type checking of programs is a precondition for the semantics to work properly, and usually type checking comes with the type ....

....systems. Whereas TEL [12, 13] allows explicit subtype relationships between polymorphic types having different arities (e.g. list(ff) my type(ff; fi) in [8] subtype relationships between polymorphic type are allowed only between type constructors of the same arity. The type system of PROTOS L [3, 1] was derived form TEL by disallowing any explicit subtype relationship between polymorphic type constructors. The type inferencing algorithms of both [12, 13] and [8] are also incomplete for the PROTOS L type system. The type inferencing algorithm we present here covers the type system of PROTOS L ....

C. Beierle and G. Meyer. Run-time type computations in the Warren Abstract Machine. Journal of Logic Programming, 18(2):123--148, February 1994.

....Modifications on term databases are not undone upon backtracking. Like all other built in features such as file input and output, also the access to the term databases is completely type safe. However, these PROTOS L extensions are not described here but in the PROTOS L User s Manual [Meyer and Beierle, 1994]. Furthermore, the following modifications where made in this revised version of the language report: ffl Sections 8, 9, and 10 now contain only brief summaries of the file handling, the OSF Motif Interface and the available built ins. A detailed description of the current version of these ....

....modifications where made in this revised version of the language report: ffl Sections 8, 9, and 10 now contain only brief summaries of the file handling, the OSF Motif Interface and the available built ins. A detailed description of the current version of these features is given in [Meyer and Beierle, 1994]. ffl Corrections of the text and of the syntax (Section 11) were made, and various language restrictions that were still valid in [Beierle et al. 1991a] have been removed. However, apart from these changes no attempt was made to update e.g. the comparison to the related work which has appeared ....

[Article contains additional citation context not shown here]

C. Beierle and G. Meyer. Run-time type computations in the Warren Abstract Machine. The Journal of Logic Programming, 18(2):123--148, February 1994.

....with more versatile constraints by including parametric polymorphism. Efficiency problems appear when it comes to implement an extended type constraint solver. For certain type systems it is possible to find several optimizations ( Smo89] which can also be realized in an Abstract Machine ([BM94]) Our experience with large systems implemented in a logic language with polymorphism and subtypes (e.g. production planning systems implemented with the PROTOS L system [BBM94, MB94] shows that there is seldom any use of complex type constraints, such as X:list(pair(nat,negint) other than ....

Christoph Beierle and Gregor Meyer. Run-time type computations in the Warren Abstract Machine. The Journal of Logic Programming, 18(2):123--148, February 1994.

....the spirit of constraint logic programming. PROTOS L ( Bei92] BBM91] Bei95] is a logic programming language that has a polymorphic, order sorted type concept (similar to the slightly more general type concept of TEL [Smo88] and a complete abstract machine implementation, called PAM ( BMS91] [BM94]) that is an extension of the WAM by the required polymorphic order sorted unification. Our aim is to provide a full specification and correctness proof of the concrete PAM system. Here we keep the notion of types and dynamic type constraints sufficiently abstract to allow applications to ....

....2 TERM type prefix(ref(l) i) 2 TYPEPREFIX with i 2 f1, arity(val(ref(l) g. 3.2. Unification Lowlevel unification in the PAM can be carried out as in the WAM (see [AK91] if we refine the bind operation into one that takes into account also the type constraints of the variables ( BMS91] [BM94]) The bind operation may thus also fail and initiate backtracking if the type constraints are not satisfied. Thus, we can use the treatment of unification as described in [BR92b] while leaving the bind operation abstract for the moment, not only in order to postpone the discussion of occur check ....

[Article contains additional citation context not shown here]

C. Beierle and G. Meyer. Run-time type computations in the Warren Abstract Machine. Journal of Logic Programming, 18(2):123--148, February 1994.

....respect to the type system the usual reaction is to reject such an approach for typed logic programming and require the resolution and its unification to obey the type constraints on variables. In that case, i.e. using an inference calculus implementing the correct order sorted unification as in [BM94], the goal absdist(5,4,D) fails. With respect to detecting the programming error in this example, the practical consequences of using or leaving out order sorted unification are essentially the same: the program is well typed but does not produce the intended results. Type correct inference ....

Christoph Beierle and Gregor Meyer. Run-time type computations in the Warren Abstract Machine. The Journal of Logic Programming, 18(2):123-- 148, February 1994.

....represents a constraint in the spirit of constraint logic programming. PROTOS L [Bei92] is a logic programming language that has a polymorphic, order sorted type concept (similar to the slightly more general type concept of TEL [Smo88] and a complete abstract machine implementation, called PAM [BM94] that is an extension of the WAM by the required polymorphic ordersorted unification. Our aim is to provide here a full specification and correctness proof of the PAM, including extra logical features and all WAM optimizations (like environment trimming and last call optimization) as well as PAM ....

....rules apply only if the involved variable has no type restriction at all (i.e. TOP) or a monomorphic, or a polymorphic type restriction, respectively. In the spirit of the WAM s tagged architecture it is thus sensible to distinguish these three different cases efficiently by special tags [BM94]. The tag VAR is therefore replaced by the three tags FREE, FREE M, FREE P. Moreover, in the representation of monomorphic sorts one can also easily save a type area location by letting the ref value of a data area location point directly to SORT. Therefore, we extend the codomain of the ....

[Article contains additional citation context not shown here]

C. Beierle and G. Meyer. Run-time type computations in the Warren Abstract Machine. Journal of Logic Programming, 18(2):123--148, February 1994.

Online articles have much greater impact   More about CiteSeer.IST   Add search form to your site   Submit documents   Feedback  

CiteSeer.IST - Copyright Penn State and NEC