For Advent of Code 2021 day 12 it took me a while to get going though for reasons unrelated to coding, Norovirus is not pleasant! So when I finally did the puzzle, I didn’t find it as difficult as I thought it would be based on some of the messages on the #adventofcode channel. The puzzle started with With your submarine’s subterranean subsystems subsisting suboptimally This deserves a medal in itself.

Advent of Code 2021 day 11 felt a little bit like a repeat of Day 9. In both cases, we got a 2-dimensional map with single digit values. In case of day 9 it was a height map, this time round we’ve got a 10x10 grid of bioluminescent Octopi. Each of those critters has an energy level that increases each round. Once that level goes past 9, it lets off a flash, which then imparts extra energy into the surrounding 8-legged creatures.

Day 10 of Advent of Code 2021 was all about mismatched brackets. And I think Haskell did rather well on this as I found the expressiveness arrived at a really concise solution. We’re still in our Advent submarine and after mapping the floor on Day 9, we now discover lots of syntax errors in the submarine navigation system. The problem This puzzle was all about matching brackets, the input was like this:

Dave Farley and Martin Fowler are two heavyweights when it comes to Software Development. As well as his latest and hugely anticipated book Modern Software Engineering, Dave wrote Continuous Delivery. Martin co-wrote the Agile Manifesto and Refactoring. All of which are hugely influential to large swathes of software engineers. So when both came together for Dave’s new series on YouTube, the Engineering Room (sponsored by Equal Experts), it was bound to be very interesting.

On day 9 of Advent of Code 2021 I arrived at two different solutions for parts one and two. That is to say the approach I took in part one turned out to be useless for part two, though I’m pleased with both solutions. Unlike yesterday’s which got a bit convoluted (Day 8). The problem This puzzle was all about looking at a height map and finding the lowest points. The input would look like so:

On day 8 Advent of Code 2021 adventure, part 1 lulled me into a false sense of security. It took longer to read the instructions than implementing the code. But then part 2 was back with a vengeance. Admittedly it would have been so much easier if I slowed down a bit and actually counted carefully. As it happened it was a good reminder that “more haste, less speed” applies to programming very much.

On the 7th day of the submarine Advent of Code 2021 adventure, I felt like the problem was getting a bit easier than it had been of late. If anything I felt a touch suspicious on whether I had been missing anything. In previous days I had to reframe the problem statement a bit to make it efficient (Day 4, Day 5 and Day 5). Either that or I’m starting to feel more comfortable with Haskell.

On the next day of Advent of Code 2021 there were two approaches to solving the problem. Brute force and ignorance, and stopping to think about it. After finding out that Haskell often forces me to having a think first on Day 4 and Day 5, I was looking forward to The problem This puzzle was all about lanternfish population - yes there was a submarine theme to this year!

Following from my efforts on Day 4 of Advent of Code 2021 I was encouraged to try writing up more of my attempts to teach myself Haskell while having fun trying to solve puzzles. The problem The exercise was concerned with drawing lines on a grid and finding intersections: An entry like 1,1 -> 1,3 covers points 1,1, 1,2, and 1,3. An entry like 9,7 -> 7,7 covers points 9,7, 8,7, and 7,7.

For Advent of Code 2021 rather than just thinking “Hey, what a good idea - I should give that a go” and then promptly forgetting about it, I thought it would be a good opportunity to explore Haskell a bit more. On day 4 - when I started scratching my head for a bit - I discovered one interesting aspect about a functionally pure approach “forced” on me by Haskell.