Abstract:Package managers are legion. Every programming language and operating system has its own solution, each with subtly different semantics for dependency resolution. This fragmentation prevents multilingual projects from expressing precise dependencies across language ecosystems; it leaves external system and hardware dependencies implicit and unversioned; it obscures security vulnerabilities that lie in the full dependency graph. We present the \textit{Package Calculus}, a formalism for dependency resolution that unifies the core semantics of diverse package managers. Through a series of formal reductions, we show how this core is expressive enough to model the diversity that real-world package managers employ in their dependency expression languages. By using the Package Calculus as the intermediate representation of dependencies, we enable translation between distinct package managers and resolution across ecosystems.
From many vantage points, it’s easy to forget the city is home to a massive 900-acre oil refinery, its imposing sprawl of stacks, holding tanks and billowing steam hidden from view. But for nearly 60 years, the refinery has loomed over every aspect of life in Benicia, exerting outsized influence on its economy and politics, while posing serious risks to public health.
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多年前，克林頓和愛潑斯坦的聯繫已為外界所知。克林頓此前聲稱，他和愛潑斯坦的關係是因自己卸任總統後致力於慈善工作而建立的。