Reddy U.S., Transformational Derivation of Programs using the FOCUS System, ACM Symposium on Software Development Environments,December 1988.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....of the termination problem, notice that the termination proof of Chin s deforestation algorithm takes four pages in [11] Chin s and Wadler s algorithms are specialized towards the deforestation tactical so that it does not seem to be flexible enough to include other tacticals. The Focus system [20] is a general system for synthesis based on rewriting techniques. However, it is not fully automatic. We do not know a fully automatic process which supports other tacticals than deforestation. Chin and Darlington have done a remarkable work to take account of higherorder functional programs in ....

U. S. Reddy. Transformational derivation of programs using the Focus system. In ACM Symposium on Practical Software Development Environments, pages 163--172, December 1988.

....That is, to evaluate an assignment VAR: EXP the EXP is evaluated both numerically and symbolically, and VAR gets a numeric value, if possible, otherways a symbolic value. 2 A number of projects have used logic programming technology for building analysis tools: for instance, Ergo [113] and Focus [157]. Ergo is an integrated set of programming tools. Among these, one is implemented in Prolog to use first order logic for reasoning in semantic domains and for program verification and synthesis. Focus is a programming environment that integrates the logic and the functional paradigms for automatic ....

U. Reddy. Transformational Derivation of Programs Using the Focus System. In Proc. 3rd ACM Symp. on Software Development Environments, volume 13:5 of ACM SIGSOFT Software Engineering Notes, pages 163--172, 1988.

....g and the definition of h must be done to find the new definition of h. Given the new function h, the function of interest f , the inductive consequences L, the means to orient equations of L, and the function g, the system or the user needs only to orient equational consequences. The Focus system [18], which does not search for equational consequences, is even more restrictive. It superposes only g and h and simplifies by rewriting. Therefore, it does no completion at all. But this is sometimes too restrictive. For example, it generates this definition of reverse as reverse(nil) nil ....

U. S. Reddy. Transformational derivation of programs using the Focus system. In Symposium Practical Software Development Environments, pages 163-172, ACM, December 1988.

....A new automatic way to implement deforestation inside the Haskell s compiler is shown in [9] General purpose program transformation systems are based on a foldingunfolding strategy a la Burstall and Darlington [4] Deforestation is a particular instance of this strategy. In the Focus system [11], folding and unfolding are seen as term rewritings. It has been pointed out in [7] how a foldingunfolding strategy can be directed by a completion procedure. Following this idea, the transformation system Astre [1, 2] is based on partial completion procedures 1 . Astre takes into account of ....

U. S. Reddy. Transformational derivation of programs using the Focus system. In Symposium Practical Software Development Environments, pages 163-172, ACM, December 1988.

....traverses the data structure only once. This is another way of transforming programs according to the tupling lemma [10] General purpose program transformation systems are based on a unfold fold method [6] Deforestation and tupling are particular instances of this strategy. In the Focus system [14], folding and unfolding are seen as rewritings. It has been pointed out in [9] that an unfold fold strategy can be controlled by a completion procedure. Following this idea, the transformation system Astre [3, 4] is based on completion procedures. Astre takes into account of inductive laws ....

U. S. Reddy. Transformational derivation of programs using the Focus system. Symp. Practical Software Development Environments, pages 163-172, ACM, December 1988.

....of rule applications are restored to their original conditions to facilitate another path of rule applications. 6 Other Approaches to Program Development This section discusses and contrasts other approaches to program development to the one addressed in this paper. A transformational approach [30, 31, 32, 33] to program synthesis typically comprises a system of rules to transform programs expressed in recursion equations of the form E ( F , into more efficient programs, where E is a function expression of the form f(e 1 ; e n ) f is a function name, and e i are expressions. The ....

....corresponding LHS instance E to obtain (F ( F 00 ) this process abstracts a function from a specification. The correctness of a final program is guaranteed since it is assumed that all transformations are equivalence preserving. In contrast to transformational approaches to program synthesis [30, 31, 32, 33], Seed uses a bottom up derivation of programs guided by the derivation of a valid wp that yields a program satisfying an abstract description of a problem. The transformational approach to program derivation depends on the user s intuition in determining appropriate places to introduce new ....

Uday S. Reddy. Transformational derivation of programs using the focus system. Extended abstract, University of Illinois at Urbana-Champaign, Champaign-Urbana, IL, August 1987.

....A new automatic way to implement deforestation inside the Haskell s compiler is shown in [9] General purpose program transformation systems are based on a folding unfolding strategy a la Burstall and Darlington [4] Deforestation is a particular instance of this strategy. In the Focus system [11], folding and unfolding are seen as term rewritings. It has been pointed out in [7] how a folding unfolding strategy can be directed by a completion procedure. Following this idea, the transformation system Astre [1, 2] is based on partial completion procedures 1 . Astre takes into account of ....

U. S. Reddy. Transformational derivation of programs using the Focus system. In Symposium Practical Software Development Environments, pages 163-172, ACM, December 1988.

....once. This is another way of transforming programs according to the tupling lemma [9] General purpose program transformation systems are based on a unfold fold method proposed by Burstall and Darlington [6] Deforestation and tupling are particular instances of this strategy. In the Focus system [13], folding and unfolding are seen as rewritings. It has been pointed out by Dershowitz [11] that an unfold fold strategy can be controlled by a completion procedure. Following this idea, the transformation system Astre [1, 2] is based on completion procedures. The first versions of Astre were ....

U. S. Reddy. Transformational derivation of programs using the Focus system. Symp. Practical Software Development Environments, pages 163-172, ACM, December 1988.

....the integration of program derivation and validation with interactive editing, compiling, debugging, and execution. 1 Introduction Program transformation systems are important tools that implement various program manipulations that preserve program semantics and improve program performance [3, 11, 12, 15, 24, 26, 28, 31]. Interactive program transformation. Program transformation systems are often required to be interactive, for at least the following two reasons. First, the goal of the system is often so ambitious that no fully automatic transformation can succeed; interaction allows convenient semi automatic ....

....useful for phase based transformations. In particular, for phases not involving circular attributes, efficient evaluators for non circular attribute grammars can be generated. 2. 4 Replay A minimal approach to replaying transformations is to record the history or script of external input [28]. Powerful metalanguages can help reduce the recording work [11] for example, with a metalanguage that allows rewrite, we can record one rewrite in place of a sequence of transformations involved in the rewrite. Replay is important not only for helping to understand the whole transformation, but ....

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U. Reddy. Transformational derivation of programs using the Focus system. In Proc. of the ACM SIGSOFT/SIGPLAN Software Eng. Symp. on Practical Software Development Environments, pages 163--172, 1988.

....as much as possible. Moreover the program transformation process requires theorem proving abilities such as ground convergence proofs, induction proofs, sufficient completness, that can be easily provided by completion procedures and other term rewriting system techniques. The system Focus [21, 22] uses rewriting and overlappings but it does not use completion procedures. The main reason is that a completion procedure is doing too much for the purpose of the transformation. That is why ASTRE limits the completion process and uses partial completion procedures . Justification of this point ....

U. S. Reddy. Transformational derivation of programs using the Focus system. In Symposium Practical Software Development Environments, pages 163-172, ACM, December 1988.

....two loops fusion or two loops tupling since it is implemented by a tuple of functions. General purpose program transformation systems are based on a unfold fold method proposed by Burstall and Darlington [7] Deforestation and tupling are particular instances of this strategy. In the Focus system [11], folding and unfolding are seen as rewritings. It has been pointed out by Dershowitz [8] that an unfold fold strategy can be controlled by a completion procedure. Following this idea, the transformation system Astre [1] is based on completion procedures. The first versions of Astre were highly ....

U. S. Reddy. Transformational derivation of programs using the Focus system. In ACM Symposium on Practical Software Development Environments, pages 163--172, December 1988.

....way to implement deforestation inside the Haskell s compiler is shown in [9] Most of the general purpose program transformation systems are based on a folding unfolding strategy a la Burstall and Darlington [4] Deforestation is a particular instance of this strategy. In the Focus system [11], folding and unfolding are seen as term rewritings. It has been pointed out in [7] how a folding unfolding strategy can be directed by a completion procedure. Following this idea, the transformation system Astre [1, 2] is based on partial completion procedures 2 . Astre takes into account of ....

U. S. Reddy. Transformational derivation of programs using the Focus system. In Symposium Practical Software Development Environments, pages 163-172, ACM, December 1988.

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Reddy U.S., Transformational Derivation of Programs using the FOCUS System, ACM Symposium on Software Development Environments,December 1988.

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Reddy U.S., Transformational Derivation of Programs using the FOCUS System, ACM Symposium on Software Development Environments, December 1988.

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Reddy U.S., Transformational Derivation of Programs using the FOCUS System, ACM Symposium on Software Development Environments, December 1988.

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