Re: [Haskell-beginners] How to nest arbitrary things

how to write an "unpack" function

is this what Lenses are all about? https://www.fpcomplete.com/school/to-infinity-and-beyond/pick-of-the-week/a-... tutorial I stumbled across Lenses only recently so can not write a working example yet. if Lenses are relevant to this topic, could someone kindly post an appropriate (Truck Parcel Can) datatype and an "unpack" with Lenses example?