haskell-lens

That at and ix are different is already noticable if you look at the available instances for the classes containing these functions: instances of At: Map, IntMap, HashMap instances of Ixed: [a], Map, ByteString, Text, and a lot more All instances if At are also an instance of Ix, but not all instances of Ix … Read more

Lenses characterise the has-a relationship; Prisms characterise the is-a relationship. A Lens s a says “s has an a“; it has methods to get exactly one a from an s and to overwrite exactly one a in an s. A Prism s a says “a is an s“; it has methods to upcast an a … Read more