`ghc-vis` doesn't support library profiling, as noted in:
> http://felsin9.de/nnis/ghc-vis/#installation
This gets the package building and it runs fine when called from ghci as you
normally would, however when you actually try viewing an expression it fails
with the following error message:
```
ghc: Error running utility program: Unable to call the command dot with the
arguments: " -Txdot " because of: dot: runInteractiveProcess: posix_spawnp:
does not exist (No such file or directory)
```
As far as I can tell that is because `ghc-vis` needs to run dot at runtime but
since it's a library adding `graphviz` as a dependency doesn't quite do the
trick.
And while not ideal adding `graphviz` to the shell you're running `ghc-vis` at
works around this issue.
777dcd7ee3