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When you release a new version of your library, please do a favor to your users and publish a changelog entry highlighting the most important changes.

The changelog tells your users what’s new – it gives them a reason to upgrade. It tells them what’s broken, so they won’t be surprised when nothing works anymore.

I’ve heard this quip that the changelog is one of the most important pieces of documentation, because even if the other documentation is lacking, it tells you what is outdated about the knowledge you have discovered yourself.

Sure, the commit history is always there, but usually it’s hard to understand. It’s easier to write a passable changelog than to curate the history.

How to do it in practice? keep a changelog has elaborate instructions. If you want to follow them, that’s great, but as long as you use a consistent format with version numbers and release dates, I’m happy.

# Write more macros

If you’re a Clojure programmer, it’s likely that you don’t write many macros. Everybody is always warning against writing too many macros. Those people are wrong: macros are great and you should write more of them.

Here are some good uses for macros:

1. Control structures keep your code simple.
2. with- macros keep your resource usage tidy.

I dislike def macros, because I often need the corresponding non-def function macros and I usually have to read the source to figure out how they differ. That said, they’re okay when they look like this:

(declare foo)

(defmacro deffoo [x & args]
(def ~x (foo ~@args)))

You could even write a macro for defining def` macros!

# Hiking from Pyhä to Luosto

Last week I hiked in the Pyhä-Luosto national park for four days. This was my first multi-day hike ever and it was great! I’m not going to post a full-blown travelogue, but I’ll try to make some notes about what made it great.

On terminology: I’m out of my depth with all these nature words. It’s hard to properly map them from Finnish to English. Figuring out the proper terms for wetlands is especially hard, so I’ll just call them mires. Sorry.

There are many reasons for hiking, but I do it because I enjoy beautiful landscapes. Pyhä-Luosto delivers: it has fells and mires. They are my favorite Finnish landscape elements. This was reflected in our pace. We walked only 10-12 km per day to have time for admiring and photographing the nature, to take detours, to cook and in general just to not be in a hurry.

Hiking in Pyhä-Luosto is easy: the routes are well-marked and all the rest spots are well-equipped. The huts even have gas stoves for cooking. This suited me well as I’m not much of a bushcraft person. The only thing that required some consideration was potable water. This is not the part of Lapland with brooks everywhere. There’s water in the mires, for sure, but the idea of drinking it didn’t exactly thrill me.

## Recommendations

If you’re planning to hike in the Pyhä-Luosto national park, here are my recommendations:

1. Go see the Isokuru gorge. Its main sight is the Pyhänkasteenputous waterfall and it’s one of the most picturesque places I’ve visited in Finland.
2. If you like mires, walk the Luosto nature trail (vaellusluontopolku). It goes through the Pyhälatva mire, showcasing different kinds of mire vegetation. If you’re there in the right time of year, you might find a lot of cloudberries, too. Unfortunately for us, they weren’t ripe yet.
3. If you’re going to climb on Ukko-Luosto, the south-east trail walks amidst beautiful rocks, shrubs, and brush. I would go up the south-east trail and take the stairs on the north-east side to get down.
4. The Lampivaara café has excellent home-made donuts.

## Lessons for the next hike

I had some packing problems. I’ll try to do better next time.

1. Use a backpack that can handle weight of your equipment. My Haglöfs internal frame backpack is a travel model, but it was supposed to withstand hiking. This turned out to be not true: I loaded it with some 20 kg of clothes, equipment, food, and water. The frame got bent and on the second day of the hike part of the frame popped out through two layers of fabric. We managed to fix it, but I don’t want to load it fully again.
2. Maybe do not pack a Trangia stove sideways in the backpack. The lid of the stove was circular when we started the trip. Now it’s oval. I don’t know what happened.
3. Go on a practice walk with the fully-packed backpack. I hadn’t used this backpack before with over 15 kg load. It took me a while to figure out how to adjust it properly for the heavy loads. I could have done it closer to home.
4. Blocky or cylindrical water bottles would make packing easier. I used two 1.5 liter soft drink bottles to carry the water. The pointy tops of the bottles made it hard to pack them efficiently.
5. Bring enough cocoa to have hot chocolate every day. Self-explanatory.
6. Bring a backup battery for the camera. The X100T battery won’t last for four days.