Update only specific field of specific item (data) in List from YAML
I don't like that I need to provide all other fields in changing node
  alike (location x) etc...


You can "update" a field of a record like so:

where enR x = if rep == location x then x { hash = Just hash } else x


I would recommend against names like fnm, dat, ed, enR, etc. You should also use consistent casing (postRebuild instead of post_rebuild).