Cargo Dependencies Management

Cargo Dependencies Management

Guidance for adding and managing dependencies in Cargo.toml files within the HASH repository's workspace structure.

Core Principles

HASH uses a strict workspace dependency pattern:

✅ DO:

• Add external dependencies to workspace root [workspace.dependencies]
• Use caret version specifiers (e.g., version = "1.0.0" = ^1.0.0)
• Set default-features = false for all dependencies unless specifically needed
• Use workspace = true in package Cargo.toml
• Organize dependencies into 4 sections with comment headers
• Use public = true for dependencies exposed in public API
• Align dependency names using spaces for readability

❌ DON'T:

• Add version numbers directly in package Cargo.toml
• Use exact versions with = prefix (e.g., =1.0.0) in workspace root
• Enable default-features without considering impact
• Mix different dependency types without section comments
• Forget public = true for dependencies exposed in public API

Quick Reference

The 4-Section Pattern

Every package Cargo.toml must organize dependencies into these sections:

[dependencies]
# Public workspace dependencies
hash-graph-types = { workspace = true, public = true }
hashql-core      = { workspace = true, public = true }

# Public third-party dependencies
serde     = { workspace = true, public = true, features = ["derive"] }