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Questions - haskell-optics

Is there an `id` of `prism' id Just`?

I have a function called: mapRouteEncoder :: Prism' FilePath FilePath -> Prism' r1 r2 -> (b -> a) -> RouteEncoder a r1 -> RouteEncoder b r2 This function is often used by spe...
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Sridhar Ratnakumar

haskell

haskell-optics

Votes: 0

Answers: 1

Latest Answer

I'm not familiar with the idioms for that package, but I'd be tempted to use castOptic equality to turn the identity Iso into a Prism. That seems to get the idea across pretty well. However, I would e...
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dfeuer

Unable to coerce during `DerivingVia` when using optics types like `Prism'`

I'm unable to automatically derive instances using DerivingVia on any type that uses types from optics-core like Prism'; the error I get from compiler is: src/Main.hs:24:13-19: error: • Couldn't m...
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Sridhar Ratnakumar

haskell

coercion

derivingvia

haskell-optics

Votes: 0

Answers: 1

Latest Answer

Generally speaking, profunctor optics (such as those used in the lens and optics packages) aren't directly coercible. Roughly speaking, the internal representation of a prism is something like: newty...
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K. A. Buhr

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