System.Which

Documentation

which :: FilePath -> IO (Maybe FilePath)

Determine which executable would run if the given path were executed, or return Nothing if a suitable executable cannot be found

staticWhich :: FilePath -> Q Exp

Run which at compile time, and substitute the full path to the executable.

This is useful in NixOS to ensure that the resulting executable contains the dependency in its closure and that it refers to the same version at run time as at compile time