Not building

[pepa65]

This is on Linux Mint 20.1 with cabal-install version 2.4.0.0-2build3. cabal new-build hwormhole:

Config file path source is default config file.
Config file /home/pp/.cabal/config not found.
Writing default configuration to /home/pp/.cabal/config
Warning: The package list for 'hackage.haskell.org' does not exist. Run 'cabal
update' to download it.
Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: hwormhole-0.2.0.1 (user goal)
[__1] unknown package: optparse-applicative (dependency of hwormhole)
[__1] fail (backjumping, conflict set: hwormhole, optparse-applicative)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: hwormhole, optparse-applicative

Tried cabal update, and then again cabal new-build hwormhole:

Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: hwormhole-0.2.0.1 (user goal)
[__1] next goal: saltine (dependency of hwormhole)
[__1] rejecting: saltine-0.1.1.1, saltine-0.1.1.0, saltine-0.1.0.2 (conflict:
hwormhole => saltine==0.1.0.1 && <1.0)
[__1] rejecting: saltine-0.1.0.1 (conflict: pkg-config package
libsodium>=1.0.13, not found in the pkg-config database)
[__1] rejecting: saltine-0.1.0.0, saltine-0.0.1.0, saltine-0.0.0.6,
saltine-0.0.0.5, saltine-0.0.0.4, saltine-0.0.0.3, saltine-0.0.0.2,
saltine-0.0.0.1 (conflict: hwormhole => saltine==0.1.0.1 && <1.0)
[__1] fail (backjumping, conflict set: hwormhole, saltine)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: hwormhole, saltine

Any pointers?

[pepa65]

I installed libsodium-dev and the rest worked!