1,566 research outputs found
A technique for doing lazy evaluation in logic
AbstractWe develop a natural technique for defining functions in logic, i.e. PROLOG, which directly yields lazy evaluation. Its use does not require any change to the PROLOG interpreter. Function definitions run as PROLOG programs and so run very efficiently. It is possible to combine lazy evaluation with nondeterminism and simulate coroutining. It is also possible to handle infinite data structures and implement networks of communicating processes. We analyze this technique and develop a precise definition of lazy evaluation for lists. For further efficiency we show how to preprocess programs and ensure, using logical variables, that values of expressions once generated are remembered for future access. Finally, we show how to translate programs in a simple functional language into programs using this technique
Logic programming in the context of multiparadigm programming: the Oz experience
Oz is a multiparadigm language that supports logic programming as one of its
major paradigms. A multiparadigm language is designed to support different
programming paradigms (logic, functional, constraint, object-oriented,
sequential, concurrent, etc.) with equal ease. This article has two goals: to
give a tutorial of logic programming in Oz and to show how logic programming
fits naturally into the wider context of multiparadigm programming. Our
experience shows that there are two classes of problems, which we call
algorithmic and search problems, for which logic programming can help formulate
practical solutions. Algorithmic problems have known efficient algorithms.
Search problems do not have known efficient algorithms but can be solved with
search. The Oz support for logic programming targets these two problem classes
specifically, using the concepts needed for each. This is in contrast to the
Prolog approach, which targets both classes with one set of concepts, which
results in less than optimal support for each class. To explain the essential
difference between algorithmic and search programs, we define the Oz execution
model. This model subsumes both concurrent logic programming
(committed-choice-style) and search-based logic programming (Prolog-style).
Instead of Horn clause syntax, Oz has a simple, fully compositional,
higher-order syntax that accommodates the abilities of the language. We
conclude with lessons learned from this work, a brief history of Oz, and many
entry points into the Oz literature.Comment: 48 pages, to appear in the journal "Theory and Practice of Logic
Programming
An Integrated Development Environment for Declarative Multi-Paradigm Programming
In this paper we present CIDER (Curry Integrated Development EnviRonment), an
analysis and programming environment for the declarative multi-paradigm
language Curry. CIDER is a graphical environment to support the development of
Curry programs by providing integrated tools for the analysis and visualization
of programs. CIDER is completely implemented in Curry using libraries for GUI
programming (based on Tcl/Tk) and meta-programming. An important aspect of our
environment is the possible adaptation of the development environment to other
declarative source languages (e.g., Prolog or Haskell) and the extensibility
w.r.t. new analysis methods. To support the latter feature, the lazy evaluation
strategy of the underlying implementation language Curry becomes quite useful.Comment: In A. Kusalik (ed), proceedings of the Eleventh International
Workshop on Logic Programming Environments (WLPE'01), December 1, 2001,
Paphos, Cyprus. cs.PL/011104
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