AgentSkillsCN

mojo-lint-syntax

依据当前 v0.26.1+ 标准对 Mojo 语法进行校验。适用于在编译前及时发现语法错误。

SKILL.md
--- frontmatter
name: mojo-lint-syntax
description: "Validate Mojo syntax against current v0.26.1+ standards. Use to catch syntax errors before compilation."
category: mojo
mcp_fallback: none

Lint Mojo Syntax

Validate Mojo code against v0.26.1+ syntax standards.

When to Use

  • •Writing new Mojo code before testing
  • •Reviewing Mojo code for syntax issues
  • •Migrating code from older Mojo versions
  • •Checking for deprecated patterns
  • •Pre-commit validation of Mojo files

Quick Reference

bash
# Validate single executable file (with main())
mojo build -I . file.mojo

# Build entire package (for library files)
mojo package shared

# Format code (fixes many syntax issues)
pixi run mojo format .

# Check for deprecated patterns
grep -r "inout self\|@value\|DynamicVector\|->" *.mojo | grep -v "result\|fn"

IMPORTANT: Library files with relative imports CANNOT be validated using mojo build - use mojo package instead.

Common Syntax Issues

Deprecated Patterns:

  • •❌ inout self → ✅ out self in __init__, ✅ mut self in methods
  • •❌ @value → ✅ @fieldwise_init with trait list
  • •❌ DynamicVector → ✅ List
  • •❌ -> (T1, T2) → ✅ -> Tuple[T1, T2]

Constructor Issues:

  • •Wrong parameter type in __init__ (must be out self)
  • •Missing trait conformances (Copyable, Movable)
  • •Incorrect initialization order

Type Issues:

  • •Missing type annotations (required in fn declarations)
  • •Mismatched types in assignments
  • •Invalid type parameters

Ownership Issues:

  • •Missing transfer operator ^ for non-copyable types
  • •Using var parameter incorrectly
  • •Copy/move semantics violations

Validation Workflow

  1. •Identify file type: Determine if file is library (has relative imports) or executable (has main())
  2. •Check syntax: Run appropriate command:
    • •Executable files: mojo build -I . file.mojo
    • •Library files: Skip standalone compilation (part of package)
  3. •Fix format: Run pixi run mojo format to auto-fix style
  4. •Verify patterns: Check for deprecated patterns
  5. •Type check: Ensure all types are correct
  6. •Ownership check: Verify ownership semantics
  7. •Package validation: Use mojo package shared for library files
  8. •Report issues: List all problems found

Output Format

Report syntax issues with:

  1. •File - Which file has the issue
  2. •Line - Line number of error
  3. •Error - Syntax error message
  4. •Pattern - What deprecated/wrong pattern was used
  5. •Fix - How to correct it
  6. •Severity - Critical (won't compile) or warning

Error Handling

ProblemSolution
Compiler not foundVerify mojo is installed and in PATH
Module not foundAdd -I . flag to include current directory
Encoding issuesConvert file to UTF-8
Version mismatchCheck mojo version against v0.26.1+
Large filesProcess one file at a time

Validation Checklist

Before committing Mojo code:

  • • File compiles with mojo build
  • • No syntax errors in compiler output
  • • No deprecated patterns (inout, @value, DynamicVector)
  • • All __init__ use out self (not mut self)
  • • All non-copyable returns use ^ operator
  • • All type annotations present in fn declarations
  • • Zero compiler warnings

References

  • •See CLAUDE.md for v0.26.1+ syntax standards
  • •See validate-mojo-patterns for pattern validation
  • •See mojo-format skill for code formatting