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I'm trying to solve the whole Advent of Code series in Haskell.

I'm encountering a memory issue while solving the 2015/06 exercise where there is a bunch of instructions to turn on, off and toggle lights on a grid. The goal is to count the number of lit lights at the end.

Given instructions are parsed and stored in a Instruction type, this is the type definition:

Problem Description: I am trying to do the task mentioned here - https://codereview.stackexchange.com/questions/182483/advent-of-code-2017-day-1-sum-of-digits-matching-the-next-digit-circular-list

But in Windows Power Shell using simple loop logic (as I am new to Power Shell)

The task requires to review a sequence of digits and find the sum of all digits that match the next digit in the list. The list is circular, so the digit after the last digit is the first digit in the list. For example:

1122 produces a sum of 3 (1 + 2) because the first digit 1 matches the second digit and the third digit 2 matches the fourth digit; 1111 produces 4 because each digit (all 1) matches the next; 1234 produces 0 because no digit matches the next; 91212129 produces 9 because the only digit that matches the next one is the last digit, 9

I have coded this:

I'm learning Haskell and I'm using Advent of Code 2015 to practice. I tried to solve Day06 with a bitlist rather than a list of coordinates and status, but it does not compute the right value and I can't understand if there's a fault in the logic or in the implementation.

Here's the code:

I've started leaning Haskell not long ago by solving this year's Advent of Code tasks.

While solving Part 2 of Day 17 I've ran into a nasty memory leak (space leak) -- I think.

_{(Here's the full README including Part 2, one can only access it after solving Part 1.)}

My solution works and it runs fine, but only with a dirty little hack, which forces Haskell to evaluate an intermediate computation every now and then.

I'm using traceShow to print the intermediate state to the console after every 5000 iterations (please see here the actual code). This way the program finishes in a reasonable time and doesn't use too much memory.

The problem: if I remove this (not printing the intermediate state at all, only the last state) the program eats up all available memory. :(

I've started out with using iterate and then I've read that using that can cause stuff like what I'm noticing. I've replaced it. Nothing. Tried different folds (foldl, foldl', etc.). Nothing. I'm not sure at this point what can cause this although my guess is that at some point there's some not so evident lazy evaluation going on.

My question: how can I avoid this? What causes this in my case?

Thank you for your time and insight. Oh, and I'm pretty sure that there are shorter, sweeter solutions to this problem, but currently I'm only interested in what causes the memory leak in my case.

I've isolated the part of the code where I notice this error.

New to Perl6, trying to figure out what I'm doing wrong here. The problem is a simple checksum that takes the difference of the max and min values for each row in the csv

The max and min values it returns are completely wrong. For the first row in the csv, it returns the max as 71, and the min as 104, which is incorrect.

Here's the link to the repo for reference, and the link to the corresponding problem.

When working on an AoC puzzle, I found I wanted to subtract lists (preserving ordering):