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Systems & Architecture 7 min read Yashvardhan Thanvi July 15, 2026

AST Syntax-Aware Normalization for JSON, XML, and YAML Prompts

Compressing Structural Data Payloads Without Invocation Failures

Mathematical intuition

Parses structured inputs into AST node trees, normalizes formatting whitespace, and prunes low-entropy array elements while validating schema structure.

  1. 01Compressing JSON or XML via raw text token truncation causes syntax errors and parse failures.
  2. 02LLMSlim format optimizers validate AST integrity before and after structural reduction.
  3. 03Safely compresses large JSON API payloads passed into function-calling LLMs.

1. Structural JSON Compression Pattern

Using format-specific modes in LLMSlim:
json_opt_example.py
from llmslim import compress

json_prompt = """{
  "request_id": "req_99281a",
  "instructions": "Extract entities from payload",
  "schema": {
    "type": "object",
    "properties": {
      "user_name": {"type": "string"},
      "user_id": {"type": "integer"}
    }
  }
}"""

# Perform AST syntax-aware normalization and compression
result = compress(json_prompt, mode="json", target_ratio=0.5)

print(f"Original Tokens: {result.original_tokens}")
print(f"Compressed Tokens: {result.compressed_tokens}")
print(result.compressed_text)
  1. [ECMA-404]The JSON Data Interchange Syntax Standard (Ecma International)