AST Manipulation

SkillMedia

Expert skill for abstract syntax tree design, traversal, transformation, and manipulation patterns

Instructions available. Your AI can read the instructions. Execution depends on the setup they require.

Account requirements not reviewed. Check the skill instructions before use; ahel provides instructions and does not run this skill.

Add ahel to your AI once: Claude, ChatGPT, Cursor, Claude Code or Codex. Then ask it to use this.

Then ask your AI: use the AST Manipulation skill

What this skill tells your AI

The instructions your AI receives, as published by a5c-ai/babysitter in library/specializations/programming-languages/skills/ast-manipulation/SKILL.md and read by ahel’s review.

Overview

Expert skill for abstract syntax tree design, traversal, transformation, and manipulation patterns.

Capabilities

Design typed AST node hierarchies
Implement visitor and transformer patterns
Build AST rewriting systems
Implement AST diffing and patching
Generate AST pretty-printers and formatters
Support AST serialization (JSON, binary)
Implement pattern matching on AST structures
Design span/location tracking systems

Target Processes

ast-design.js
semantic-analysis.js
ir-design.js
code-generation-llvm.js
lsp-server-implementation.js
macro-system-implementation.js

Dependencies

None (core skill)

Usage Guidelines

Node Design: Design immutable AST nodes with clear ownership semantics
Location Tracking: Include source spans on all nodes from the beginning
Visitor Pattern: Implement visitor pattern for extensible traversal
Transformation: Use transformer pattern for AST-to-AST transformations
Serialization: Support both human-readable (JSON) and efficient (binary) serialization

Output Schema

{
  "type": "object",
  "properties": {
    "nodeTypes": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "name": { "type": "string" },
          "fields": { "type": "array" },
          "parent": { "type": "string" }
        }
      }
    },
    "visitors": {
      "type": "array",
      "items": { "type": "string" }
    },
    "transformers": {
      "type": "array",
      "items": { "type": "string" }
    },
    "generatedFiles": {
      "type": "array",
      "items": { "type": "string" }
    }
  }
}

Signals

GitHub stars: 2k
Forks: 112
Last commit: Sep 2026

Advanced

Item type: skill
Key: ast-manipulation
Source: github.com/a5c-ai/babysitter

github.com/a5c-ai/babysitter