Package

Move is a language for writing smart contracts - programs that are stored and run on the blockchain. A single program is organized into a package. A package is published on the blockchain and is identified by an address. A published package can be interacted with by sending transactions calling its functions. It can also act as a dependency for other packages.

Package consists of modules - separate scopes that contain functions, types, and other items.

package 0x...
    module a
        struct A1
        fun hello_world()
    module b
        struct B1
        fun hello_package()

Package Structure

Locally, a package is a directory with a Move.toml file and a sources directory. The Move.toml file - called the "package manifest" - contains metadata about the package, and the sources directory contains the source code for the modules. Package usually looks like this:

sources/
    my_module.move
    another_module.move
    ...
tests/
    ...
examples/
    using_my_module.move
Move.toml

The tests directory is optional and contains tests for the package. Code placed into the tests directory is not published on-chain and is only availably in tests. The examples directory can be used for code examples, and is also not published on-chain.

Published Package

During development, package doesn't have an address and it needs to be set to 0x0. Once a package is published, it gets a single unique address on the blockchain containing its modules' bytecode. A published package becomes immutable and can be interacted with by sending transactions.

0x...
    my_module: <bytecode>
    another_module: <bytecode>

Package

Package Structure

Published Package

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