Type Safety Validation Skill

Ensure Mojo code follows type safety principles.

When to Use

• Type errors during compilation
• Code review for type safety
• Designing generic functions
• Working with trait constraints

Quick Reference

# Generic function with type parameter
fn add[dtype: DType](a: Scalar[dtype], b: Scalar[dtype]) -> Scalar[dtype]:
    return a + b

# Trait constraint
fn process[T: Copyable](data: T):
    let copy = data  # T is Copyable

# Compile-time check
@parameter
fn validate[size: Int]():
    constrained[size > 0, "Size must be positive"]()

Workflow

1. Add type annotations - All parameters and returns
2. Use type parameters - For generic code
3. Add trait constraints - When required
4. Run compiler - Verify type checking passes
5. Test generic code - With multiple types

Mojo-Specific Notes

• Prefer fn over def for type safety
• Generic type parameters use [T] syntax
• Traits constrain what operations are allowed
• Compile-time checks prevent runtime errors

Error Handling

| Error | Cause | Solution | |-------|-------|----------| | Missing type annotation | Untyped parameter | Add : Type to parameter | | Type mismatch | Incompatible types | Add explicit conversion | | Unsupported operation | Trait not constrained | Add trait constraint | | Constraint failed | Compile-time check failed | Verify constraint conditions |

References

• .claude/shared/mojo-guidelines.md - Current syntax and patterns
• .claude/shared/mojo-anti-patterns.md - Common constructor mistakes