H. Kuchen, R. Loogen, J.J. Moreno-Navarro, and M. Rodrguez-Artalejo. Lazy Narrowing in a Graph Machine. In Proc. of the Int'l Conf. on Algebraic and Logic Programming, volume 463 of Lecture Notes in Computer Science, pages 298--317, 1990.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....between needed narrowing and another (not so lazy) narrowing strategy which is the basis for popular implementations of lazy functional logic languages. We demonstrate that needed narrowing and lazy narrowing are computationally equivalent over the class of uniform programs introduced in [16, 17]. We also introduce a complete refinement of lazy narrowing, called uniform lazy narrowing, which is still equivalent to needed narrowing over the aforementioned class. Since actual implementations of functional logic languages are based on the transformation of the original program into a ....

.... This work investigates and clarifies the formal relation between needed narrowing and another (not so lazy) narrowing strategy which was introduced in [22] where it is called lazy narrowing and is the basis for the implementation of several lazy functional logic languages like, e.g. [12, 16, 22]. Our main contributions are the following: 1. Needed narrowing and lazy narrowing are computationally equivalent over the class of uniform programs introduced in [16, 17] i.e. both strategies compute the same answers and values over this class of programs. 2. This is the broadest class of ....

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H. Kuchen, R. Loogen, J.J. Moreno-Navarro, and M. Rodrguez-Artalejo. Lazy Narrowing in a Graph Machine. In Proc. of the Int'l Conf. on Algebraic and Logic Programming (ALP'90), pages 298--317. Springer LNCS 463, 1990.

....another (not so lazy) demand driven narrowing strategy which is the basis for popular implementations of non strict functional logic languages. We demonstrate that needed narrowing and demand driven lazy narrowing are computationally equivalent over the class of uniform programs introduced in [12, 13], i.e. both strategies compute the same answers and values over this class of programs. We also introduce a complete re nement of demand driven lazy narrowing, called uniform lazy narrowing, which is still equivalent to needed narrowing over the aforementioned class. Since actual ....

....same answers and values over this class of programs. We also introduce a complete re nement of demand driven lazy narrowing, called uniform lazy narrowing, which is still equivalent to needed narrowing over the aforementioned class. Since actual implementations of functional logic languages [9, 12, 14, 15, 18] are based on the transformation of the original program into a uniform one, which is then executed using the (demand driven) lazy narrowing strategy, our results can be thought of as a formal basis for the correctness of these implementations. Keywords: formal semantics, programming ....

[Article contains additional citation context not shown here]

H. Kuchen, R. Loogen, J.J. Moreno-Navarro, and M. Rodrguez-Artalejo. Lazy Narrowing in a Graph Machine. In Proc. of ALP'90, pages 298-317. Springer LNCS 463, 1990.

....f has the form f(x k , c i (y n i ) z m ) where x k , y n i , z m are pairwise di#erent variables and the constructors c i are distinct in di#erent rules. In the latter case, an evaluation of a call to f demands its (k 1) th argument. A di#erent definition of uniform programs can be found in [34]. 3 The idea of needed narrowing can also be extended to almost orthogonal programs [11] but then the optimality properties are lost. 11 There is a simple mapping U from inductively sequential into uniform programs which can be found in [50] and is based on flattening nested patterns. For ....

H. Kuchen, R. Loogen, J.J. Moreno-Navarro, and M. Rodrguez-Artalejo. Lazy Narrowing in a Graph Machine. In Proc. of the Int'l Conf. on Algebraic and Logic Programming, volume 463 of Lecture Notes in Computer Science, pages 298--317, 1990.

....standard Curry semantics and the incremental one, our work can be thought of as a formal warranty that compiling functional logic programs into Prolog code is not only simple and practical but also reliable. A similar argument applies to those implementations based on abstract narrowing machines [KLMR90] which also enjoy the incrementality implicitly which is embedded into standard compilation techniques. On the other hand, programmers working on other implementation techniques can also rely on the present work for achieving incremental evaluation safely. Although it cannot compete with an ....

H. Kuchen, R. Loogen, J.J. Moreno-Navarro, and M. Rodrguez-Artalejo. Lazy Narrowing in a Graph Machine. In Proc. of the Int'l Conf. on Algebraic and Logic Programming, pages 298-317. Springer LNCS 463, 1990.

....xk ; yn i ; zm are pairwise different variables and the constructors c i are distinct in different rules. In the latter case, an evaluation of a call to f demands its (k 1) th argument. Uniform programs are inductively sequential. A different definition of uniform programs can be found in [35]. There is a simple mapping U from inductively sequential into uniform programs which can be found in [51] and is based on flattening nested patterns. For instance, if R is the set of rules defining 6 (see Example 3.1) then U(R) consists of the rules 0 6 n True S(m) 6 n m 6 0 n m 6 0 ....

H. Kuchen, R. Loogen, J.J. Moreno-Navarro, and M. Rodr'iguez-Artalejo. Lazy Narrowing in a Graph Machine. In Proc. of ALP'90, pages 298--317. Springer LNCS 463, 1990.

....f has the form f(x k ; c i (y n i ) z m ) where x k ; yn i ; z m are pairwise different variables and the constructors c i are distinct in different rules. In the latter case, an evaluation of a call to f demands its (k 1) th argument. A different definition of uniform programs can be found in [34]. There is a simple mapping U from inductively sequential into uniform programs which can be found in [50] and is based on flattening nested patterns. For instance, if R is the program in Example 1, then U(R) consists of the rules 0 6 N true s(M) 6 N M 6 0 N M 6 0 0 false M 6 0 s(N1) ....

H. Kuchen, R. Loogen, J.J. Moreno-Navarro, and M. Rodr'iguez-Artalejo. Lazy Narrowing in a Graph Machine. In Proc. of the Int'l Conf. on Algebraic and Logic Programming, volume 463 of Lecture Notes in Computer Science, pages 298--317, 1990.

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H. Kuchen, R. Loogen, J.J. Moreno-Navarro, and M. Rodrguez-Artalejo. Lazy Narrowing in a Graph Machine. In Proc. of the Int'l Conf. on Algebraic and Logic Programming, volume 463 of Lecture Notes in Computer Science, pages 298--317, 1990.

No context found.

H. Kuchen, R. Loogen, J.J. Moreno-Navarro, and M. Rodr'iguez-Artalejo. Lazy Narrowing in a Graph Machine. In Proc. of the Int'l Conf. on Algebraic and Logic Programming, volume 463 of Lecture Notes in Computer Science, pages 298--317, 1990.

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