Observe
COOSy is an implementation of a lightweight approach for debugging functional logic programs written in Curry by observations. It consists of a library plus a viewing tool. Programmers can annotate their program with observation functions for data structures and functions which may both contain or be applied to logical variables. The parts of observed objects that are evaluated during the execution are recorded in a trace file and can be viewed by means of a pretty printer integrated in a graphical user interface. The tool covers all aspects of modern functional logic multiparadigm languages such as lazy evaluation, higher order functions, non-deterministic search, logic variables, concurrency and constraints.
The implementation of COOSy is freely available and an interface to COOSy is integrated in the distribution of the Curry programming environment PAKCS. To use COOSy in PAKCS, the implementation must be installed locally, which can be done by installing this package with the command
cypm install coosyDetails about COOSy and its implementation can be found in this paper:
B. Brassel, O. Chitil, M. Hanus, F. Huch: Observing Functional Logic Computations, Proc. of the Sixth International Symposium on Practical Aspects of Declarative Languages (PADL’04), Springer LNCS 3057, pp. 193-208, 2004
There are also slides about COOSy which has been presented at PADL 2004.
In contrast to the version described in the original paper, the
current version also considers the fact that free variables can only
occur in expressions with a Data context (see the paper Adding Data to
Curry for a detailed explanation). Therefore, the current
observation tool distinguishes the observation of expressions with or
without a Data context: the operation
Observe.observe can observe expressions containing free
variables which are instantiated during the evaluation (which is the
main innovation of COOSy), whereas the operation
Observe.observeG can also observe expressions without a
Data context but requires that they are always instantiated
(otherwise, the observation might suspend). Since functional values have
no Data context, one has to distinguish how to observe the
arguments. For instance, observers with observer type
(oList oInt ~> oList oInt)can observe functions which are possibly invoked with free variables and might return a free variable, whereas
(oList oInt ~~> oList oInt ~~> oInt)observe functions which are possibly invoked with free variables but return a non-free results and
(oList oInt ~~~> oList oInt ~~~> oMaybe oInt)observe functions which are called with non-free arguments and return non-free results.
The examples directory contains various programs
containing observers.
| Developed by |
| * Bernd Brassel (CAU Kiel, Germany, bbr@informatik.uni-kiel.de) * Olaf Chitil (University of Kent, UK, O.Chitil@kent.ac.uk) * Michael Hanus (CAU Kiel, Germany, mh@informatik.uni-kiel.de) * Frank Huch (CAU Kiel, Germany, fhu@informatik.uni-kiel.de) |
| Version of September 20, 2024 |