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arXiv · 2210.00758

Reflections on existential types

Jonathan Sterling
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Abstract

Existential types are reconstructed in terms of small reflective subuniverses and dependent sums. The folklore decomposition detailed here gives rise to a particularly simple account of first-class modules as a mode of use of traditional second-class modules in connection with the modal operator induced by a reflective subuniverse, leading to a semantic justification for the rules of first-class modules in languages like OCaml and MoscowML. Additionally, we expose several constructions that give rise to semantic models of ML-style programming languages with both first-class modules and realistic computational effects, culminating in a model that accommodates higher-order first-class recursive modules and higher-order store.

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Jonathan Sterling. 2022-10-03. Reflections on existential types. https://arxiv.org/abs/2210.00758

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