I really want to use lenses. The idea of a definition that allows lossless translation from one data representation to another is so elegant. But I wonder if it's a mathematical ideal that doesn't match up with real world problems? I thought to apply the concept of a lens in my problem domain, converting engineering files to machine readable config files, but the reality is the process is more like combining multiple inputs to form an output, which may not contain all of the input data. So I'm left applying some tricks (including unnecessary data in the output/input) to make the process act like a lens. And it's pretty error prone.

Are there applications for lenses that really allow lossless translation in both directions? Or am I misunderstanding the concept in some fundamental way?