This book constitutes the refereed proceedings of the 7th Asian Symposium on Programming Languages and Systems, APLAS 2009, held in Seoul, Korea, in December 2009. The 21 papers presented in this volume together with 3 invited talks were carefully reviewed and selected from 56 submissions. The papers are divided into topical sections on program analysis, transformation and optimization, type system, separation logic, logic and foundation theory, software security and verification, and software security and verification.

Inhalt
Invited Talks.- The Twilight Zone: From Testing to Formal Specifications and Back Again.- Types and Recursion Schemes for Higher-Order Program Verification.- The Sketching Approach to Program Synthesis.- Program Analysis.- Large Spurious Cycle in Global Static Analyses and Its Algorithmic Mitigation.- Abstract Transformers for Thread Correlation Analysis.- Scalable Context-Sensitive Points-to Analysis Using Multi-dimensional Bloom Filters.- Transformation and Optimization.- A Short Cut to Optimal Sequences.- A Skeletal Parallel Framework with Fusion Optimizer for GPGPU Programming.- Witnessing Purity, Constancy and Mutability.- Type System.- On the Decidability of Subtyping with Bounded Existential Types.- Fractional Ownerships for Safe Memory Deallocation.- Ownership Downgrading for Ownership Types.- Separation Logic.- A Fresh Look at Separation Algebras and Share Accounting.- Weak updates and separation logic.- Proving Copyless Message Passing.- Logic and Foundation Theory.- On Stratified Regions.- Parallel Reduction in Resource Lambda-Calculus.- Classical Natural Deduction for S4 Modal Logic.- Software Security and Verification.- Bi-abductive Resource Invariant Synthesis.- Certify Once, Trust Anywhere: Modular Certification of Bytecode Programs for Certified Virtual Machine.- Asymptotic Resource Usage Bounds.- The Higher-Order, Call-by-Value Applied Pi-Calculus.- Branching Bisimilarity between Finite-State Systems and BPA or Normed BPP Is Polynomial-Time Decidable.- Refining Abstract Interpretation-Based Static Analyses with Hints.