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Comment by crazygringo | Hacker News Reader

But... it usually does. For example, try:

    Decimal('3.0') / 2

It works fine. It doesn't work with a float, which is for good reason. That's the whole point -- its general philosophy is to be pretty liberal with types, except when there's a good reason not to be. Heck, you can even do dumb things like:

    4 + True

And get 5 back. If that's not "blindly interchanging different types for no good reason" then I don't know what is. You can even multiply your Decimal object by False and get an answer...

Or it's like my original example -- the Regex module isn't restricted to r-strings. It happily works with regular strings. Python's general philosophy is to handle input liberally. Even type hinting is an add-on. Now, it doesn't go as far as JavaScript in allowing e.g. "4"+1, but it's still awfully liberal. I just don't see how you can claim otherwise.

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I know about Decimal/int mixing but that’s for a good reason: it’s fine to intermix here. But not for floats (precision issues). The bool/int mixing isn’t “good.” It’s a bad implementation detail that Python is stuck maintaining forever. I’m actually stunned that you think to use this as an example when I think I’d fire any programmer that did that in my team for gross negligence.

The reason it works is because Python functionally has no bool type. True and False are just integers with names. It’s stupid and shouldn’t work like that but it does for historic reasons.

Your example of regex makes no sense either. There is no difference between strings and r-strings. They’re literally the same thing to the interpreter, so how could the regex functions enforce you use r-strings? Maybe they should be different but, for historic reasons, they can’t be without Python 4.0.

> I’m actually stunned that you think to use this as an example when I think I’d fire any programmer that did that in my team for gross negligence.

You seem to be having a different conversation than I am.

I'm just describing Python as it is. I'm not defending it. I know why you can add True to a number, or else I wouldn't have come up with the example. And I know perfectly well that r-strings are just strings. Python easily could have made them a distinct object, to force people from ever making backslash errors, and restricted Regex functions to them, but didn't.

My only point has been, "Pythonic" things tend to be pretty liberal in what they accept. Type hints aren't even enforced, when they exist at all. You seem to think it shouldn't be that way. Great! But regardless, claiming it's not that way -- that Python is somehow this strict language -- is just mischaracterizing it.

> My only point has been, "Pythonic" things tend to be pretty liberal in what they accept

Being able to use a string as a string and an int as an int are not “pretty liberal in what they accept,” it’s just programming language theory 101! I think you’re mistaking duck typing for “liberal acceptance,” which are not the same thing. There’s always been an expectation that you should use compatible interfaces, even within the standard library. I’ve been bitten enough times by passing a generator in when a function expects a list, for example.

I'm not mistaking it at all. Yes, duck typing is very much liberal acceptance, but Python code tends to go much farther. I could give a million examples -- like how in Python's isinstance() the second argument can be a type or a tuple of types, or in sqlite3 that you can run queries on a connection or on a cursor, and don't even get me started on Matplotlib or Numpy. It's just idiomatic in Python to make things easy for the programmer by accepting multiple types when possible. If you don't recognize this as the common Python pattern, I literally don't know what else to tell you.

> The reason it works is because Python functionally has no bool type. True and False are just integers with names.

This has not been true since around 2.4 or 2.5. The oldest Python I have available to me currently is 2.7, and this holds then, as it does now in 3.13:

    >>> type(True)
    <class 'bool'>
    >>> type(1)
    <class 'int'>

Prior to having a bool type, Python didn't even have True/False keywords.

The reason something silly like `4 + True` works is because the bool type implements `tp_as_number` [0]. The reason it works this way is intentional because it would been a Python 3 str-style debacle if ints and bools were not interchangeable.

[0] https://github.com/python/cpython/blob/main/Objects/boolobje...

> its general philosophy is to be pretty liberal with types, except when there's a good reason not to be.

And there’s a good reason not to be here.

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