The main lensy tools for maps are the At and Ixed classes, both found in Control.Lens.At.

On Mon, Jun 17, 2019, 11:45 PM Henry Laxen <nadine.and.henry@pobox.com> wrote:
Hi Cafe,

Suppose I have:

s :: Map String (Map Int Char)
s =  M.fromList [("alice", M.fromList [(5,'a')]), ("bob", M.fromList [(6,'b')])]

Is there any way to modify the 'b' entry easily using lenses?

Thanks in advance.
Best wishes,
Henry Laxen

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