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... Starting base16-bytestring-0.1.1.6 Starting data-default-class-0.1.2.0 Building data-default-class-0.1.2.0 Building base16-bytestring-0.1.1.6 Completed data-default-class-0.1.2.0 Completed base16-bytestring-0.1.1.6 Starting toxcore-c-0.2.11 Failed to install toxcore-c-0.2.11 Build log ( /home/builder/.cabal/logs/ghc-8.6.3/toxcore-c-0.2.11-FCtWnQGWSxu4ha61puKaDT.log ): cabal: Entering directory '/tmp/cabal-tmp-25323/toxcore-c-0.2.11' Configuring toxcore-c-0.2.11... cabal: Missing dependencies on foreign libraries: * Missing (or bad) C libraries: toxcore, toxcore This problem can usually be solved by installing the system packages that provide these libraries (you may need the "-dev" versions). If the libraries are already installed but in a non-standard location then you can use the flags --extra-include-dirs= and --extra-lib-dirs= to specify where they are.If the library files do exist, it may contain errors that are caught by the C compiler at the preprocessing stage. In this case you can re-run configure with the verbosity flag -v3 to see the error messages. cabal: Leaving directory '/tmp/cabal-tmp-25323/toxcore-c-0.2.11' cabal: Error: some packages failed to install: toxcore-c-0.2.11-FCtWnQGWSxu4ha61puKaDT failed during the configure step. The exception was: ExitFailure 1