[keithasaurus]

Hey... I'm the maintainer and had no idea this was posted. The reason pure is required is because it's clear and opt-in. There's a CLI subcommand called purify that will help identify pure functions that haven't been deemed so if that's desired.

But there can be many (small) applications where pure doesn't even matter, so I don't really want to force someone to write "impure" for the main function, for example.