infinisil: it's only printing
 ```building Nix...                                                                                                         
building the system configuration...                                                                                    
trace: Get `stack-sha256` with `nix-hash --base32 --type sha256 /nix/store/n0nsxsfd28138n2d7xi8vrdxk5njfqp0-stack-to-nix-pkgs/`
building '/nix/store/vrpcm2j4aliw5z6giqvbfm85y5is56yb-ghc-8.6.5.drv'...    
```
before starting the ghc build