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# Categories for Optics

New paper by Mitchell Riley, putting optics - the technique popularised in Haskell for accessing and modifying state in a highly general way - on a sound categorical footing.

https://arxiv.org/abs/1809.00738

Despite being familiar with lens/optics usage in Haskell, I'm finding this paper very difficult, although this course has certainly helped. Profunctors feature heavily of course, as do end/coends, which I have so far found impenetrable.

Comment Source:I glimpsed over the first page, and what I knew for years as **getters** and **setters** - just functions which allow you to do additional stuff while modifying a **property**, here called a **lens**, or in other words lens is a readable and writeable property. I wonder whether other stuff, like prisms, may bring something new to the table (don't know what are these though). Maybe someone who knows this better may explain in layman terms?