The type of van Laarhoven lenses forall f. Functor f => (i -> f i) -> o -> f o seems to be made for effectful updates i -> f i. At least so I believed. And I had to pay dearly because of that. Read the full story in my blogpost at: How to shoot yourself in the foot with lenses and state | shoot-y…

How to shoot yourself in the foot with lenses and state

rhendric September 6, 2024, 6:58pm 3

A while back there was some discussion of a combinator like modifyM in a lens issue.

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