The ability to install more than one library with a command like cabal install <name of library>, use them together and not have confusing messages pop up about hidden libraries.
If I try to learn about the ‘v2-’ commands I get a lot of out of date and strange information. Eventually I find myself at the official documentation and after clicking around decide what I’m probably supposed to be doing is a ‘nix-style local build’. I don’t know what a local build is, or what nix is or therefore what it means to be in that style. So I read on further and that it combines non-sandboxed and sandboxed cabal. So that’s two more things I don’t understand. This really feels quite impenetrable. So I just try to use commands like the v1- ones I already know. Somehow if I run cabal install tidal cabal identifies that I want to install a library, but doesn’t install the library as a library and asks me to re-run the command with a --lib option to do that. I comply but quickly get to the point where my ‘default package environment’ is broken (the same library installed more than once) and go back to using the ‘v1-’ versions that worked.