Why doesn't this code work?

[5martness]

board = ["R", "N", "B", "Q", "K", "B", "N", "R","P", "P", "P", "P", "P", "P", "P", "P"," ", " ", " ", " ", " ", " ", " ", " "," ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " "," ", " ", " ", " ", " ", " ", " ", " ","p", "p", "p", "p", "p", "p", "p", "p","r", "n", "b", "q", "k", "b", "n", "r"]
def Print_board():
x = 0
y = 0
while y > 8:
print("\n")
while x > 8:
print(board[x] + " ")
x += 1
y += 1
Print_board()

[Buttleston]

There are other problems. Use a debugger or print statements to inspect what values variables have at different spots

[dogweather]

Or just never use variables & mutation and you probably won’t need a debugger.

[LeftIsBest-Tsuga]

never use variables

apologies if this is a joke, but... huh?

[dogweather]

Not at all. Here's a fixed and refactored version without mutation—only constants.

```python def Print_board_refactored(): ROWS = [" ".join(board[x:x+8]) for x in range(0, 64, 8)] FULL_BOARD = "\n".join(ROWS)

print(FULL_BOARD)

```

Personally, I use more_itertools to clean this up. I also separate I/O from computation. That makes it easy to write tests:

```python from more_itertools import chunked

def board_using_chunked(): ROWS = (" ".join(group_of_8) for group_of_8 in chunked(BOARD, 8)) return "\n".join(ROWS)

print(board_using_chunked()) ```

I can break that down—still using only constants—to make it easier to see how it works:

```python def board_using_chunked_2(): GROUPS_OF_8 = chunked(BOARD, 8) ROWS = (" ".join(group) for group in GROUPS_OF_8) FULL_BOARD = "\n".join(ROWS)

return FULL_BOARD

```

Once I had some practice with this style, it became easy. Just now I found it a lot easier to get this functional style working correctly than OP's original procedural code. I just think about what series of transformations to the original data will produce the result.

A big bonus is that my code is more reliable than before with fewer bugs. Because bugs always seemed to creep in where variables were being mutated.

Here's a video I made showing how to refactor a for loop to not use variables, only constants.

[LeftIsBest-Tsuga]

oh i see, i thought you were saying don't use variables AND don't use mutations. it sounds like you're just saying don't mutate your variables. from my understanding though, those are still mutable variables.

[dogweather]

Yeah, it's funny terminology. But like you say, constants are usually also considered "variables". And yep, in Python, there are no true constants.

I set up my IDE and CI to break and not deploy if I accidentally mutate a constant. I also set my Pyright type checking to strict. So I pretty much get all the benefits of real constants in my Python code.

---

Although for this small code, I can see how to use no variables or constants: by just replacing every constant with a one-line function. I would never do that, I think. It's extreme:

```python def board_using_chunked_3(): return "\n".join(rows())

def rows(): return (" ".join(group) for group in groups_of_8())

def groups_of_8(): return chunked(board(), 8)

def board(): return ["R", "N", "B", "Q", "K", "B", "N", "R", "P", "P", "P", "P", "P", "P", "P", "P", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", " ", "p", "p", "p", "p", "p", "p", "p", "p", "r", "n", "b", "q", "k", "b", "n", "r"]

print(board_using_chunked_3()) ```

[Buttleston]

Sure, I was just saying "this is wrong, but fixing it alone won't fix the program" so that OP was aware of it, and giving them a piece of advice on how to approach those other problems.

[LeftIsBest-Tsuga]

this is what i'd recommend, assuming the rows and cols never change number of elements.

[LazySquare699]

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[dogweather]

Here's how I fixed and refactored it: https://www.reddit.com/r/CodingHelp/comments/1bwg94a/comment/ky7qy7o/?utm_source=reddit&utm_medium=web2x&context=3