As already explained elsewhere: [Haskell Cryptography Group] Botan: The First Milestone - #14 by hasufell
3.3.0 is in debian experimental and oddly enough, windows is likely the least problematic platform.
I tried to create a botan-clib package, but the build system is a disaster: which source files to compile depends on platform and processor features that are detected during “configure”. You’ll have to map those things manually in the cabal file and create flags for all the cpu features, because the c source files used need to be encoded in the cabal file. And then review the build system changes on every version bump.
These are things that e.g. a gentoo or nixpkgs developer would be comfortable to do, but it isn’t at all trivial. And you lose the automagic detection of features.
Another way might be to abuse custom setup really hard, but that’s not gonna be very popular or easy either.