Hello scarpet world?
Note
This is curently only available on Fabric.
Note
You'll need to install CarpetMod.
Script profession installation
- Download the script professions you want and put them in 
minecraft-folder/world/scripts. - Run the server / singleplayer.
 - Make sure the script is loaded (
/script load <script name>). (To autoload the scripts, use/carpet setDefault scriptsAutoload true) - Give taterzen the 
taterzens:scarpet_profession(/npc edit professions add taterzens:scarpet_profession). 
Creating a merchant
Download the merchant script and load it using the steps described above.
Now you can trade:
16 oak_log(s)for3 emerald(s)32 stonefor2 gold.
Modifying scripts
Do you want to add trades to the above example? Simply add new items in the global_item_map.
global_item_map = {
    // Takes 32 stone and gives 2 gold
    'stone' -> {
        'take_count'-> 32,
        'trade_item'-> 'gold',
        'trade_count'-> 2
    },
    // Takes 16 oak_log(s) and gives 3 emerald(s)
    'oak_log' -> {
        'take_count'-> 16,
        'trade_item'-> 'emerald',
        'trade_count'-> 3
-    }
+    },
+    // Takes 1 dirt and gives 64 diamond. Stonks!
+    'dirt' -> {
+        'take_count'-> 1,
+        'trade_item'-> 'diamond',
+        'trade_count'-> 64
    }
};
Also check out scarpet wiki and docs for help with custom script creation.