Warning: The install command is a part of the legacy v1 style of cabal usage.

Please switch to using either the new project style and the new-install
command or the legacy v1-install alias as new-style projects will become the
default in the next version of cabal-install. Please file a bug if you cannot
replicate a working v1- use case with the new-style commands.

For more information, see: https://wiki.haskell.org/Cabal/NewBuild

Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] next goal: sdl2-ttf (user goal)
[__0] rejecting: sdl2-ttf-2.1.1 (conflict: pkg-config package
SDL2_ttf>=2.0.12, not found in the pkg-config database)
[__0] rejecting: sdl2-ttf-2.1.0, sdl2-ttf-2.0.2, sdl2-ttf-2.0.1,
sdl2-ttf-2.0.0, sdl2-ttf-1.0.0, sdl2-ttf-0.2.2, sdl2-ttf-0.2.1, sdl2-ttf-0.2.0
(constraint from user target requires ==2.1.1)
[__0] fail (backjumping, conflict set: sdl2-ttf)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: sdl2-ttf