Invited Talk -- On Preferring and Inspecting Abductive Models -- User Interfaces and Environments -- Declarative Programming of User Interfaces -- Huge Data But Small Programs: Visualization Design via Multiple Embedded DSLs -- Toward a Practical Module System for ACL2 -- Networks and Data -- Declarative Network Verification -- Operational Semantics for Declarative Networking -- Ad Hoc Data and the Token Ambiguity Problem -- Multi-threading and Parallelism -- High Level Thread-Based Competitive Or-Parallelism in Logtalk -- Implementing Thread Cancellation in Multithreaded Prolog Systems -- Interoperating Logic Engines -- Databases and Large Data Sets -- High-Level Interaction with Relational Databases in Logic Programming -- Typed Datalog -- Using Bloom Filters for Large Scale Gene Sequence Analysis in Haskell -- Tabling and Optimization -- One Table Fits All -- Recycle Your Arrays! -- Towards a Complete Scheme for Tabled Execution Based on Program Transformation -- Language Extensions and Implementation -- Improving Performance of Conformant Planners: Static Analysis of Declarative Planning Domain Specifications -- Layered Models Top-Down Querying of Normal Logic Programs -- Secure Implementation of Meta-predicates.

This book constitutes the refereed proceedings of the 11th International Symposium on Practical Aspects of Declarative Languages, PADL 2009, held in Savannah, GA, USA, in January 2009, colocated with POPL 2009, the Symposium on Principles of Programming Languages. The 18 revised full papers presented together with 1 invited talk were carefully reviewed and selected from 48 submissions. The volume features original work emphasizing novel applications and implementation techniques for all forms of declarative concepts, including functions, relations, logic, and constraints. The papers address all current aspects of declarative programming; they are organized in topical sections on user interfaces and environments, networks and data, multi-threading and parallelism, databases and large data sets, tabling and optimization, as well as language extensions and implementation.