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+Besides some smaller fixes with the styling of the page, and in particular the diagrams introduced in [`2019-10-24`][2019-10-24],
+I finally (re-)implemented children-ordering in the `fs`-store of mmmmfs
+(the `sql` store is still missing it, but I am not currently using it either) \[[`a62f63b`][a62f63b]\]:
+Files on the regular filesystem don't have a particular order, but in mmmfs the order of children is is guaranteed,
+so that arranging children in a particular order becomes a meaningful tool.
+
+To store the ordering data, a 'magic' file called `$order` is (optionally) stored in each directory in the filesystem.
+The file lists all child fileders by name in the given order.
+When the children of a fileder are requested (in `list_fileders_in` or `get_index`, which relies on the former),
+all children that are mentioned in `$order` are returned in that order,
+while all remaining children are sorted alphabetically and appended at the end of the list.
+This way the order is guaranteed to be stable even if no `$order` file is specified,
+or when the `$order` file has not been updated after adding new children.
+
+Here is the commented implementation in MoonScript:
+
+      list_fileders_in: (path='') =>
+        -- create a mapping of all child-fileders
+        -- in 'entries' (name -> path)
+        entries = {}
+        for entry_name in lfs.dir @root .. path
+          continue if '.' == entry_name\sub 1, 1
+          entry_path = @root .. "#{path}/#{entry_name}"
+          if 'directory' ~= lfs.attributes entry_path, 'mode'
+            continue
+
+          entries[entry_name] = "#{path}/#{entry_name}"
+
+        -- where we will store our sorted list of children
+        sorted = {}
+
+        -- check for existance of the order file
+        order_file = @root .. "#{path}/$order"
+        if 'file' == lfs.attributes order_file, 'mode'
+          for line in io.lines order_file
+            path = assert entries[line], "entry in $order but not on disk: #{line}"
+            
+            -- add all $order-entries to the sorted output in the same order they appear.
+            -- also flag these entries as already added
+            table.insert sorted, path
+            sorted[line] = true
+
+        -- find the he remaining (non-flagged) entries, sort them alphabetically
+        -- and then append them to the sorted output list
+        entries = [path for entry, path in pairs entries when not sorted[entry]]
+        table.sort entries
+        for path in *entries
+          table.insert sorted, path
+
+        -- return an iterator over the sorted output
+        coroutine.wrap ->
+          for path in *sorted
+            coroutine.yield path
+
+The interface for reordering fileders is still missing in the code,
+and just while writing this I realized that the current implementation is in fact buggy:
+when a fileder that is mentioned in `$order` is deleted via the `stores.fs` API,
+it is not removed from `$order`, causing an error the next time the fileder is listed.
+I will probably get around to fixing both of these problems when I build the corresponding UI.
+
+[2019-10-24]: /articles/mmmfs/ba_log/2019-10-24/
+[a62f63b]: https://git.s-ol.nu/mmm/commit/a62f63bc00cd63a98b349a2574e3e9e14c95a441/