F-strings

F-strings are a readable approach to building new strings from existing strings & variables.

PRQL

1. from employees
2. select full_name = f"{first_name} {last_name}"

SQL

1. SELECT
2. CONCAT(first_name, ' ', last_name) AS full_name
3. FROM
4. employees

This can be much easier to read for longer strings, relative to the SQL approach:

PRQL

1. from web
2. select url = f"http{tls}://www.{domain}.{tld}/{page}"

SQL

1. SELECT
2. CONCAT(
3. 'http',
4. tls,
5. '://www.',
6. domain,
7. '.',
8. tld,
9. '/',
10. page
11. ) AS url
12. FROM
13. web

Note that currently interpolations can only contain plain variable names and not whole expressions like Python, so this won’t work:

PRQL

1. from tracks
2. select length_str = f"{length_seconds / 60} minutes"

Error

1. Error:
2. ╭─[:2:37]
3. │
4. 2 │ select length_str = f"{length_seconds / 60} minutes"
5. │                                     ┬
6. │                                     ╰── unexpected end of input while parsing interpolated string
7. ───╯

Roadmap

In the future, f-strings may incorporate string formatting such as datetimes, numbers, and padding. If there’s a feature that would be helpful, please post an issue.