Your first pack

poplar new hello_pack
cd hello_pack
poplar build

poplar new creates this folder:

hello_pack/
├── poplar.json          the project config
├── poplar.schema.json   lets your editor check poplar.json
├── src/main.poplar      starts with `namespace hello_pack;`
└── .gitignore           ignores poplar-out/

src/main.poplar has one function:

namespace hello_pack;

mcfun load() {
    /say Hello from hello_pack!;
}

mcfun load runs every time the pack loads. poplar build writes the datapack to poplar-out/hello_pack/, and a zip of it to poplar-out/hello_pack.zip for sharing:

✓ Built hello_pack in 20 ms → poplar-out/hello_pack (1 function, zip)

Copy the folder or the zip into a world’s datapacks folder, open the world and run /reload.

While you work, poplar watch can build and copy the pack for you:

poplar watch --world ~/.minecraft/saves/"My World"

It builds every time you save a file and copies the pack into the world’s datapacks/ folder. Run /reload in the game to load the latest build.

To avoid typing --world each time, put the world in a .env file in the project folder. poplar new adds .env to .gitignore, because the path is specific to your machine:

.env

POPLAR_WORLD="~/.minecraft/saves/My World"