Lens products

[cfhammill]

From Control.Lens.Unsound

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lensProduct :: ALens' s a -> ALens' s b -> Lens' s (a, b)

A lens product. There is no law-abiding way to do this in general. Result is only a valid Lens if the input lenses project disjoint parts of the structure s. Otherwise "you get what you put in" law

view l (set l v s) ≡ v

is violated by

>>> let badLens :: Lens' (Int, Char) (Int, Int); badLens = lensProduct _1 _1
>>> view badLens (set badLens (1,2) (3,'x'))
(2,2)

but we should get (1,2).

Are you looking for alongside?

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The answer is yes, we are probably looking for alongside.

[cfhammill]

I have casually accepted too much pain instead of just writing alongside