advent-of-code-2017 | Code 2017 edition by Jeroen Heijmans | Learning library

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.