Turns out the Rust version with clap is 50x SLOWER! 54.41 to be exact. ¹

Rust usually runs close to C speeds for equivalent implementations, so the speed difference is likely all overhead from the library.

50x hit to performance. Just so you can have some magic macros for your command line interface.

TIL, clap will slow down the startup times. But it's just call only "once" while parsing aruments.

Sort of balance between usablitiy and extre performace?

JSON (JavaScript Object Notation) was supposed to be the universal data interchange format that would solve the compatibility nightmares of XML. What looks like astraightforward data format becomes a minefield of subtle incompatibilities, edge cases, and implementation quirks that can break your applications in unexpected ways.¹

Common pitfalls (selected by myself from the article):

• The Number Nightmare
  • not only precision loss for large integers
  • but also NaN and Inf, see also Daniel Lemire's tweet ²
• String Encoding Chaos
  • The character é can be represented as:
    • A single codepoint: U+00E9 (é)
    • Composed form: U+0065 U+0301 (e + ́)
• Object Key Ordering
  • It's fun that this may influence LLM KV cache performance now
• Null vs. Undefined vs. Missing
• Date and Time Fun

Authors' Recommendations:

• Use Schema Validation: The First Law of JSON Robotics
• Normalize Data Types
• Library Selection Matters
• Test Cross-Language Compatibility

May the Parse Be With You