Hi everyone,

I am very excited to share with you a PEP that Batuhan Taskaya, Lysandros Nikolaou and myself have been working on recently: PEP 701 - PEP 701 – Syntactic formalization of f-strings. 

We believe this will be a great improvement in both the maintainability of CPython and the usability of f-strings.

We look forward to hearing what you think about this and to get your feedback!

Here is a TLDR for your convenience:

• The PEP proposes a formalized grammar for f-strings in Python by adding f-strings directly into the Grammar instead of using a two-pass hand-written parser.
• This would lift some existing restrictions for f-strings that (we believe) will improve the user experience with f-strings.
• Other benefits include:
  • Reduced maintenance costs for f-string parsing code as well as improved usability for users and library developers.
  • Better error messages involving f-strings by leveraging the PEG parser machinery.
  • The proposed changes would improve the overall consistency of the language and provide a way for alternative implementations to accurately implement f-strings.

** IMPORTANT: direct all discussions to the discussion thread on discourse: https://discuss.python.org/t/pep-701-syntactic-formalization-of-f-strings/22046 **

Thanks a lot, everyone for your time!

Regards from rainy London,

Pablo Galindo Salgado