What are the pros and cons of a language using whitespace vs. {}'s to indicate scope? [closed]

Question

There seems to be a conflict over whether its better to use whitespace or tokens like brackets to indicate scope. I've seen many praise python's solution to the inconsistent indentation problem, but many disagree:

Any language that has whitespace as tokens needs to die.

posted later on the same answer:

I was sortof anti-whitespace-as-tokens, until I actually tried it. It probably helped that my personal white-space layout pretty much matches what everyone in python-land uses. Perhaps it's that I am a bit minimalist, but if you're going to indent anyways, why bother with the {}s?

I can see some clear arguments for each side:

using whitespace:

• helps reduce inconsistent indentation in code
• clears the screen by replace visible tokens with whitespace to serve the same purpose

using tokens:

• much easier to cut and paste code to different levels (you don't have to fix the indentation)
• more consistent. Some text editors display whitespace differently.
• more popular currently.

Are there any points I missed? Which do you prefer? Any words of wisdom after having worked with one or the other for a long time?

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PS. I hate it when languages don't use the same token for each control structure. VB is really annoying with its End If and End While statements, most other languages just use {}'s for everything. But maybe that's a topic for a different question...

Answer 1

I think a lot of us programmers (myself included) have a tendency to "logicalize" every decision. That's fine, but not every question has a logical answer. For instance, I doubt that chefs post questions on chefoverflow (if such a thing exists) asking for the pros and cons of apple pie vs cherry pie. It's a question of which you like better.

With that in mind, I think the simplest answer is to say "Some people like braces, some people like whitespace" and leave it at that.

Answer 2

At the risk of sounding like an utter fanboy, I think everyone who claims that whitespace “helps reduce inconsistent indentation in code” has never used Visual Studio. With a single command (I think the default shortcut is Ctrl+K,D), all the indentation is instantaneously consistent¹. Furthermore, when pasting code the indentation is instantaneously corrected without having to do anything at all, and the same is true when writing new code or when wrapping something in an if or some other block (reformat happens as the } is typed). Furthermore, pressing Enter after a completed statement always places the cursor at the correct indentation level for the next statement, even if the previous statement was indented further because of an if or similar, making it very difficult to accidentally think that a statement is still under an if when it isn’t.

The point I’m trying to make is not that Visual Studio is great. The point I’m trying to make is that the IDE can automate indentation-fixing (and other formatting issues), but only if the meaning of the program does not depend on its formatting. This gives the programmer a greater opportunity to focus on the actual programming task. A syntax like Python’s is counterproductive: it is not possible to write an IDE that can “fix” the indentation of Python code because the indentation itself specifies some of the semantics.

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¹ _{(I know there is a special case which VS refuses to reformat, namely array literals that span multiple lines, but that’s beside the point.)}

Answer 3

Personally I find I need the blank line introduced by having a token on it's own line to make my mind realise that the code is in another scope.

I hate it when in python people go:

if something
    do something
    do somethingelse

    cleanup
else
    do the other thing

while in token land I hate when people copy and paste and don't clean up the indentation,

if something
{
I have been too lazy
      {
            to clean up
            }
what I pasted
}

or don't use a separate line for the token.

if something {
    I find this confusing
}
else {
especially when combined with the previous 
do something
}

I can read all three, but they aren't as I expect and I have to expend effort to parse them and as Joel says when things don't work like you expect it makes you frustrated.

Answer 4

Pro: There are no indentation/curly-brace-placement holy wars in the Python world as far as I know. Making this decision on behalf of developers has probably saved some pain.

Con: Anonymous functions are limited to one line. Sounds ok, but I frequently find myself writing up multi-line lambdas in Scheme (mostly to feed to map or apply in exactly one place, so it wouldn't make sense to declare separately).

Answer 5

The problem I found with a whitespace language was with multi-page conditional expressions. Adding a line in the middle of page two, and getting off by one space in the middle of all mess, can drastically alter the logic of your code. And even if someone's code is "correct", trying to read it makes a terrible guessing game. Which "if" is this 'else' for? I can count braces much easier than I can count invisible blank characters. And the posting machinery on this site keeps smashing them into a single space.

IMHO "{{{{{" is more reliable than "     ".

Answer 6

{} adds redundancy. Too much redundancy is bad, too few is bad. And manualy entering it is bad, esp. if its hard to use it.

So in times of bad/no IDE, whitespace style could be slightly better. But with powerfull IDE, braces are better.

Answer 7

I don't think it's really a versus.
Pythoneers often criticize braces programmers as if they would readily violate indentation because they can.
In fact I always used 100% consistent indentation even before knowing about Python and its indentation scoping.

The fact is that braces languages could also impose correct indentation in the compiler and we would have the best of both worlds. See? no versus at all.

Pythoneers would argue that braces are useless when indentation is part of the syntax, but they are not, braces improve readability. I tried programming Python and it's a very interesting language for me, but have you tried having if-elif chains of more than 2 or 3 indentation levels? they don't look so neat anymore.

PS: I wrote braces but in a more general way, I mean delimiter tokens. The opening brace can be seen as redundant, but a language could go like this (in fact I'm sure there are languages exactly like this but I don't know them well):

if condition:
    statement
    other_statement()
end

PS2: 2019, 4 years after this answer. I learned Python and totally got used to its semantic indentation and don't find it difficult to read at all. Especially with the aid of modern IDEs that draw vertical bars to aid in identifying indent blocks.