dcmp | 基于etcd的配置管理系统 | Configuration Management library

Quoting the OCaml Towards Clarity and Grace style guide:

Code is more often read than written - make the life of the reader easy

and

Less code is better, cryptic code is worse

The first makes me think that the version with multiple when clauses is the better choice, as it makes it easy to predict or evaluate the result when reading the code depending on condition. The second goes further, against the if-then-else because, even if shorter, is cryptic when looking from afar.

Also, in the section Functions, we find out that "Pattern matching is the preferred way to define functions"

From a Haskell functional programmer's point of view.

All you need in order to mange this is queue. First add root dir to queue and then run some code with logic below:

1. Pop item from queue.
2. List items in the destination (like dir command)
3. In the list (from step 2) there are 2 type of objects you need to handle
   1. files you can check if they exists in the source (by name or by binary shape (check them by hash)) (location in the source should be the location queue)
   2. folders adding its path to a queue and recheck from step 1
4. If any thing didn't exist in source (either in step 3.1 or 3.2) copy them (or any other operation you should do)