Add string interpolation syntax that only accepts values of type String.

[Pragrammist]

Add string interpolation syntax that only accepts values of type String.

Example:

"Hello {name}!"

This should be equivalent to concatenation and must not perform implicit type conversions. Non-string values should result in a compile-time error.

This keeps interpolation ergonomic while preserving explicitness and type safety.

Alternatively, a syntax like "Hello <>name<>" could be considered for backward compatibility, avoiding {}-style interpolation while still improving readability over manual concatenation.

[lpil]

What are the motivations and use cases for this language change?

What would make it different from the existing syntax for building up strings from other strings?

[Pragrammist]

In short:

Still predictable type behavior (no hidden conversions)

But

• Better readability (the string looks like its final form)
• Lower mental overhead (no need to reconstruct concatenations)
• Faster and cleaner to write

Long:

The primary motivation is readability and reduction of cognitive overhead.
When building strings through concatenation, especially long or structured ones, the developer has to mentally reconstruct the final output by piecing together multiple fragments. This becomes increasingly difficult as the string grows in size or complexity. You’re effectively “parsing” the final string in your head.
String interpolation keeps the text in a form that is much closer to the final output. This makes it significantly easier to read, write, and reason about—particularly for long strings or templates.
From a usability standpoint, it is simply faster and less error-prone to write. Concatenation introduces visual noise (<>, quotes, line breaks), which obscures the actual content.

[lpil]

So it is that you are having problems understanding the concatenation operator? Could you share examples of the confusing code so we can better understand the problem. Thank you.