@INPROCEEDINGS{ChristiansenHanusReckSeidel13PPDP,
author = "Christiansen, J. and Hanus, M. and Reck, F. and Seidel, D.",
title = "A Semantics for Weakly Encapsulated Search in Functional Logic Programs",
year = "2013",
pages = "49-60",
publisher = "ACM Press",
booktitle = "Proc.\ of the 15th International Symposium on
             Principle and Practice of Declarative Programming (PPDP'13)"
abstract = {
Encapsulated search is a key feature of (functional) logic
languages. It allows the programmer to access and process
different results of a non-deterministic computation within a
program. Unfortunately, due to advanced operational features
(lazy evaluation, partial values, infinite structures), there is
no straightforward definition of the semantics of encapsulated
search in functional logic languages. As a consequence, various
proposals and implementations are available but a rigorous
definition covering all semantical aspects does not exist. In
this paper, we analyze the requirements of encapsulated search
in a functional logic language like Curry and provide a
comprehensive definition that covers weak encapsulation, a
modular form of encapsulation, as well as nested applications of
search operators. We set up a denotational semantics that
distinguishes non-termination and different levels of failures
in a computation. The semantics is also the basis of a
practical implementation of search operators in the functional
logic language Curry.
}
}