Dependencies

Dependencies allow you to use code from other ingots in your project. Fe supports both local path dependencies and remote git dependencies.

The [dependencies] Section

Add dependencies to your fe.toml:

[ingot]
name = "my_project"
version = "1.0.0"

[dependencies]
utils = "../shared/utils"
token_lib = { source = "https://github.com/example/token-lib.git", rev = "a1b2c3d4e5f6" }

Local Path Dependencies

Reference ingots on your local filesystem:

Simple Path Syntax

[dependencies]
my_lib = "../path/to/my_lib"

Explicit Path Syntax

[dependencies]
my_lib = { path = "../path/to/my_lib" }

Both forms are equivalent. The path is relative to your project’s fe.toml.

Example: Monorepo Structure

my-workspace/
├── contracts/
│   ├── fe.toml
│   └── src/lib.fe
└── shared/
    ├── utils/
    │   ├── fe.toml
    │   └── src/lib.fe
    └── types/
        ├── fe.toml
        └── src/lib.fe

contracts/fe.toml

[ingot]
name = "contracts"
version = "1.0.0"

[dependencies]
utils = "../shared/utils"
types = "../shared/types"

Git Remote Dependencies

Pull ingots from git repositories:

[dependencies]
token_lib = { source = "https://github.com/example/token-lib.git", rev = "abc1234" }

Required Fields

Field	Description
source	Git repository URL
rev	Git commit hash (full or abbreviated)

Note: Only commit hashes are supported for rev. Tags and branch names are not allowed because Fe does not yet support lock files. Pinning to exact commits ensures reproducible builds.

Optional Fields

Field	Description
path	Subdirectory within the repository containing the ingot

Examples

Pin to a specific commit:

[dependencies]
lib = { source = "https://github.com/org/repo.git", rev = "a1b2c3d4" }

Use a subdirectory in the repository:

[dependencies]
contracts = { source = "https://github.com/org/monorepo.git", rev = "e7f8a9b0c1d2", path = "packages/contracts" }

Using Dependencies

Once declared, import from dependencies using their name:

// Import from the 'utils' dependency
use utils::calculate_fee
use utils::SafeMath

// Import from the 'token_lib' dependency
use token_lib::ERC20
use token_lib::Transfer

The dependency name in fe.toml becomes the root of the import path.

Dependency Names

The name you give a dependency determines its import path:

[dependencies]
# This ingot is imported as 'helpers'
helpers = "../some/path/to/utils"

// Import using the name 'helpers', not the directory name
use helpers::some_function

Version Conflicts

If two dependencies require different versions of the same ingot, you may encounter conflicts. Strategies to resolve:

• Update dependencies to use compatible versions
• Use path dependencies to control exact versions
• Contact dependency maintainers about version compatibility

Summary

Dependency Type	Syntax
Local (simple)	name = "path/to/ingot"
Local (explicit)	name = { path = "path/to/ingot" }
Git remote	name = { source = "url", rev = "ref" }
Git with path	name = { source = "url", rev = "ref", path = "subdir" }