Tag strings

This PEP introduces tag strings for custom, repeatable string processing. Tag strings are an extension to f-strings, with a custom function -- the "tag" -- in place of the f prefix. This function can then provide rich features such as safety checks, lazy evaluation, domain specific languages (DSLs) for web templating, and more.

Tag strings are similar to JavaScript tagged templates <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals#tagged_templates>_ and similar ideas in other languages.

Examples repo

To keep the conversation here focused on the PEP, we moved supporting material to a companion repo. There you can find resources such as:

• JupyterLite playground for tag strings
• Docker builds
• Long-form tutorials
• Example code

Related Work

• Flufl i18n substitutions
• Tagged library
• PEP 501: Interpolation templates
• Earlier work by the same authors