GHC.BaseDir

Note [Base Dir] ~~~~~~~~~~~~~~~~~ GHC's base directory or top directory containers miscellaneous settings and the package database. The main compiler of course needs this directory to read those settings and read and write packages. ghc-pkg uses it to find the global package database too.

In the interest of making GHC builds more relocatable, many settings also will expand `${top_dir}` inside strings so GHC doesn't need to know it's on installation location at build time. ghc-pkg also can expand those variables and so needs the top dir location to do that too.

Documentation

expandTopDir :: FilePath -> String -> String

Expand occurrences of the $topdir interpolation in a string.

expandPathVar :: String -> FilePath -> String -> String

expandPathVar var value str

replaces occurrences of variable $var with value in str.

getBaseDir :: IO (Maybe String)

Calculate the location of the base dir