libghc-directory-tree-dev 0.12.1-7build2 (amd64 binary) in ubuntu lunar

 A simple directory-like tree datatype, with useful IO functions and Foldable
 and Traversable instance
 .
 Provides a simple data structure mirroring a directory tree on the
 filesystem, as well as useful functions for reading and writing
 file and directory structures in the IO monad.
 .
 This package provides a library for the Haskell programming language.
 See http://www.haskell.org/ for more information on Haskell.