minecraft-data 
This library provides support for creating mindcraft levels (.mca files) and commands (that can be entered in the game console).
At the moment it only contains low-level primatives. The support for levels, blocks, player, etc is relatively complete, though has not yet been updated for Minecraft 1.10.
The next step is to add some high level combinators.
An example showing how to generate a chunk in a level can be found at:
https://github.com/stepcut/minecraft-data/blob/master/utils/GenWorld.hs
At the moment, the only command which is implemented is Give:
https://github.com/stepcut/minecraft-data/blob/master/Minecraft/Command.hs
Patches welcome!
Much of the data comes from here:
http://minecraft.gamepedia.com/Data_values
This site looks promising as well:
https://www.digminecraft.com/lists/item_id_list_pc.php
The flattening in 1.13 and later,
The building combinators were introduced by Tim Philip Williams is this blog post
http://www.timphilipwilliams.com/posts/2019-07-25-minecraft.html
- jeremy