Type inference is the process of constructing a typing derivation while gradually discovering type information. During this process, inference algorithms typically make subtle decisions based on the derivation constructed so far.

Twilight STM enhances a transaction with twilight code that executes between the preparation to commit the transaction and its actual commit or abort. Twilight code runs irrevocably and concurrently with the rest of the program. It can detect and repair potential read inconsistencies in the state of its transaction and may thus turn a failing transaction into a successful one. Moreover, twilight code can safely use I/O operations while modifying the transactionally managed memory.

The ICFP programming contest is a 72-hour contest, which attracts thousands of contestants from all over the world. In this report we describe what it takes to organise this contest, the main ideas behind the contest we organised, the task, how to solve it, how we created it, and how well the contestants did.

Sharing analysis and uniqueness typing are static analyses that aim at determining which of a program's objects are to be used at most once. There are many commonalities between these two forms of usage analysis. We make their connection precise by developing an expressive generic analysis that can be instantiated to both sharing analysis and uniqueness typing. The resulting system, which combines parametric polymorphism with effect subsumption, is specified within the general framework of qualified types, so that readily available tools and techniques can be used for the development of implementations and metatheory.