Imports

DEAL has five import forms. All resolve through deal.toml [dependencies] and are vendored into .deal/deps/ by deal install.

The Five Import Forms

1. External import (standard library / published dependency)

import deal.std.units.{kg, km, hr, kWh, min, degC, s};

Resolves the deal.std.units package from the deal-std dependency declared in deal.toml. The braces list the specific symbols to import.

2. Workspace alias import

package vehicle.motor;

import interfaces.{HVDCPort, RegenPowerPort, CANBus, ShaftPort};

interfaces is a workspace alias declared in deal.toml [workspace.aliases]. The braces list the specific symbols to import. To import every exported symbol from a package, use a star glob: import reqs.system.*;

3. Relative same-package import

import .dimensions.{Mass, Length, Time, Current, Temperature};

The leading . resolves relative to the current package. This is used by deal-stdlib internally to share dimension definitions across units.

4. Relative parent-package import

The .. prefix navigates to the parent package, then into a sibling:

import ..sib.{SomeDef};

Use sparingly — workspace aliases are clearer for cross-package references.

5. Barrel glob import

import interfaces.*;
import vehicle.*;

Imports all exports from the package root (index.deal barrel file). Use when you need most symbols from a package.

Aliased import

Any form can be aliased:

import interfaces as intf;

After this, use intf.HVDCPort to qualify names from the package.

Selective Exports (index.deal)

Packages control their public surface via index.deal barrel exports:

export electrical.{HVDCPort, CANBus};
export mechanical.{BoltPattern};

Symbols not listed in index.deal are package-private.

deal.toml Dependency Declaration

Dependencies are declared in deal.toml [dependencies]. The deal-std stdlib is an explicit git dependency:

[dependencies]
deal-std = { git = "https://github.com/deal-lang/deal-stdlib", tag = "v0.4.0" }

After deal install, the dependency is vendored into .deal/deps/deal-std/ at the pinned commit SHA.

Local-path dependencies reference a sibling directory without copying:

[dependencies]
my-lib = { path = "../my-lib" }

deal.lock

deal install generates a SHA-pinned lockfile. For git dependencies:

[packages.deal-std]
source = "git+https://github.com/deal-lang/deal-stdlib?tag=v0.4.0"
sha = "abc1234..."

Exact refs only — no semver ranges. Commit deal.lock to reproduce the build.

Resolution Flow

deal install reads deal.toml [dependencies]
Git deps are cloned into .deal/deps/<name>/ at the locked ref
deal check and deal build add vendored sources to the analysis set
Import deal.std.units.{kg} resolves: deal-std → .deal/deps/deal-std/packages/units/si.deal → attribute def kg