How to create symlink with Haskell?

Question

How to create a symlink with Haskell? The directory package to my knowledge does not provide a way to do it.

Answer 1

directory-1.3.1 has

createFileLink :: FilePath -> FilePath -> IO ()

This is supposed to work even on Windows – only on a suitable file system, of course.

Answer 2

Creating a symbolic link is non-portable. For example, the creation symbolic links on Windows is re­strict­ed¹. Therefore it does not fit into directory providing "a basic set of operations for ma­nip­u­lat­ing files and directories in a portable way" (emphasis mine). This affects all platform independent packages.

The platform specific package unix provides that functionality in System.Posix.Files with createSymbolicLink though:

import System.Posix.Files (createSymbolicLink)

main :: IO ()
main = createSymbolicLink "/opt/ghc/7.10.3" "/opt/ghc/active"

_{1: That's also a reason why unix-compat does not implement createSymbolicLink}