entrytree_replace :: Entry a => [EntryTree a] -> Loc -> EntryTree a -> [EntryTree a]
entrytree_replace et loc enew =
    fst $ entrytree_replace_f et loc $ \_ -> ([enew], ())
entrytree_replace :: Entry a => [EntryTree a] -> Loc -> EntryTree a -> [EntryTree a]
entrytree_replace et loc enew =
    fst $ entrytree_replace_f et loc $ \_ -> ([enew], ())
entrytree_replace et loc enew =
    fst $ entrytree_replace_f et loc $ \_ -> ([enew], ())