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.
For implementers, there's no Transformer protocol with start(), transform(), flush() methods and controller coordination passed into a TransformStream class that has its own hidden state machine and buffering mechanisms. Transforms are just functions or simple objects — far simpler to implement and test.
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In a letter to its customers, Heraeus Medical said it had experienced a critical machine failure at its main site when it was in the process of upgrading its production processes.
GM Matthew Wadsworth won in Ryde on tiebreak, Scottish GM Matthew Turner also shared first, while in Graz Scotland’s Freddy Waldhausen Gordon, 15, qualified for the IM title