The F# Advent Calendar is back—and we’d love you to be part of it. Since 2014, F# developers have used this December tradition to share the things they’ve built, learned, and wondered about. This is our 13th edition, and it’s a chance to hear from the whole community: newcomers and veterans, library authors and curious tinkerers, people solving everyday problems and people exploring ideas just for fun.
From December 1 through Christmas Eve, there are 24 main dates to fill, with bonus posts welcome when there’s more to share. Your contribution doesn’t need to be a grand project or an exhaustive guide. A useful technique, a small experiment, a story from a project, or a lesson you learned can give someone else a new idea to try.
Got something F#-related you’d like to share? Choose a date and join us in making this year’s calendar a celebration of the language and the people around it. 🧑🎄
How to take part
- Pick an F#-related topic and reserve a date by posting on BlueSky, X, or leaving a comment on this post. You can keep your topic secret until publication day if you like.
- Prepare a blog post or video in English.
- Publish it on your assigned date.
- Post the link to your post on BlueSky or X with hashtags #fsharp and #FsAdvent.
| ID | Date | Author | Post Title |
|---|---|---|---|
| #2601 | Dec 01 (Tue) | Shayan Habibi | |
| #2602 | Dec 02 (Wed) | Mathias Brandewinder | |
| #2603 | Dec 03 (Thu) | ||
| #2604 | Dec 04 (Fri) | ||
| #2605 | Dec 05 (Sat) | ||
| #2606 | Dec 06 (Sun) | Sam Smucny | |
| #2607 | Dec 07 (Mon) | Matthew Watt | |
| #2608 | Dec 08 (Tue) | Adam Davies | |
| #2609 | Dec 09 (Wed) | Millennium | |
| #2610 | Dec 10 (Thu) | ||
| #2611 | Dec 11 (Fri) | Patrick Stevens | A deterministic .NET runtime for simulation testing |
| #2612 | Dec 12 (Sat) | Will Ehrendreich | |
| #2613 | Dec 13 (Sun) | shalokshalom | |
| #2614 | Dec 14 (Mon) | Adrian Sieradzki | Asking the Laws of Physics Questions in F# |
| #2615 | Dec 15 (Tue) | Iain Schmitt | |
| #2616 | Dec 16 (Wed) | Angel Munoz | |
| #2617 | Dec 17 (Thu) | Vinh Nguyen | |
| #2618 | Dec 18 (Fri) | Guy Buss | |
| #2619 | Dec 19 (Sat) | ||
| #2620 | Dec 20 (Sun) | ||
| #2621 | Dec 21 (Mon) | Pawel Stadnicki | |
| #2622 | Dec 22 (Tue) | ||
| #2623 | Dec 23 (Wed) | ||
| #2624 | Dec 24 (Thu) |
Advent of Code
Alongside the F# Advent Calendar, we have a private Advent of Code board for people solving the December puzzles with F#. If you’re taking part this year, join us and tackle the challenges alongside fellow F# developers. Whether you’re aiming to solve every puzzle or just joining in when you can, you’re welcome.
History of F# Advent
F# Advent Calendar is a long tradition in the F# community
- F# Advent Calendar in English: 2025, 2024, 2023, 2022, 2021, 2020, 2019, 2018, 2017, 2016, 2015, 2014
- F# Advent Calendar (in Japanese): 2025, 2024, 2023, 2022, 2021, 2020, 2019, 2017, 2016, 2015, 2014, 2013, 2012, 2011, 2010
That inspired the C# Advent Calendar, Q# Advent Calendar, and many others.
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Hi! I’ll take Monday, December 7
Thank you, Dec 7th is booked for you!
I guess I’ll take 1st of Dec if that’s okay?
Yes, Dec 1st is booked for you. Thanks
I’d love to do a presentation about sagefs on the 12th
Thanks! Dec 12th is booked for you.
Could I take December 15th?
Absolutely, Dec 15th is booked for you and thank you.
21st please
Thanks, Dec 21th is booked for you.
Dec 8th please? Could maybe do another too if needed.
Dec 8th is booked for you. Thank you! I’ll contact you in the second half of November if it is hard to fill the remaining slots.
Dec 9th please
Dec 9th is booked for you, thanks!
Sign me up please, any day will do!
Thanks you Mathias! Dec 2nd is booked for you.
Hi Sergey,
I wrote an article about building Sabota, an experimental mutation testing tool for F# and some unexpected lessons learned along the way:
https://danlup.com/lessons-from-sabota/
Not looking for a calendar slot, but since bonus contributions are welcome I thought I’d share it.
Can you sign me up for Dec 6th please.
Sure, Dec 6th is booked for you. Thanks!
Please reserve the Dec 13 (Sun) for me, thanks.
Done, Dec 13th is booked for you. Thanks!
Hi Sergey, thank you for keeping F# Advent going!
Could I reserve Dec 17 (Thu) please? (Happy to take Dec 19 or Dec 10 as a backup if Dec 17 is already taken.)
I’m planning a post/demo on how F#’s pure domain modeling subset projects cleanly to a visual “graybox” diagram right in the browser (exact title TBD). Thanks!
Sure, Dec 17th is booked for you, and thank you for your participation.