minecraft-assets/data/minecraft/recipes/purple_dye.json

{
  "type": "crafting_shapeless",
  "ingredients": [
    {
      "item": "minecraft:blue_dye"
    },
    {
      "item": "minecraft:red_dye"
    }
  ],
  "result": {
    "item": "minecraft:purple_dye",
    "count": 2
  }
}