Error stating 3 is not an integer?

[CubicMelon]

Error stating 3 is not an integer?

[CFiggers]

Your (length part-list) is returning 3, which means your loop is going to run a total of four times (because you're starting at zero, so it will run for i = {0, 1, 2, 3}). But a zero-indexed array with three elements only goes up to a max of 2.

To fix it, you could decrement that value (like this: (dec (length part-list))) so that you only run the loop three times (on 0, 1, 2).

EDIT: Although actually, looking at the body of your loop, you're incrementing the i to get the next element in the array. So that will go out of bounds when the loop runs on i = 2. You might want to try (- 2 (length part-list)) instead of what I wrote above.

EDIT AGAIN: Actually I think I was wrong above, because the :range keyword in (loop) goes UP TO the second number but doesn't include it. So only decrementing the counter a single time should be fine, only because you're looking one ahead in the body of the loop 🙂

[sogaiu]

I think the message is saying that the expectation was for a value that is 0, 1, or 2, but it got 3.

IIUC, the [0, 3) notation is from math -- a half-open interval (so 0 is included but 3 is not).

May be you are familiar already, but FWIW, there are some details in this section of a Wikipedia page (no direct link -- searching for "half-open" may get one closer).

[CubicMelon]

That was it, I had to decrement the end of the range by 1 because I was looking one index ahead each loop! That's what I get for trying to write this overnight. Thanks so much for helping me understand.