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.
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Photograph: Julian Chokkattu
老爸知道自己喊人抬牛的做法危险，他也怕再麻烦亲戚们，说自己记住了教训，以后会将牛犊拴起来。在农村，将一头牛拴住最保险的方式，是用一个铁环硬生生扎过牛的鼻孔，再套上连接槽边木桩的绳索，牛会因为怕疼，不敢摆脱缰绳逃跑。