Researcher question – what's the point of semicolons and curly braces?

[Chris via Digitalmars-d]

On Wednesday, 4 May 2016 at 05:27:43 UTC, tsbockman wrote:
> On Wednesday, 4 May 2016 at 05:19:35 UTC, Joe Duarte wrote:
>> I remember that Rob Pike explained why Go requires braces by 
>> recounting how at Google their tools sometimes lost or damaged 
>> the indentation in Python source files, breaking those 
>> programs. I would think that you'd just fix your tools in that 
>> case.
>
> You're not going to even try to fix it until you realize it's 
> broken, and you won't succeed until you figure out which 
> line(s) got messed up.
>
> Without any redundancy in the syntax, minor corruption of the 
> code could easily result in a program that still "works" - that 
> is, compiles and runs without producing an error message - but 
> whose behaviour has subtly changed. With redundant syntax, on 
> the other hand, the compiler is more likely to detect and 
> pinpoint the problem immediately.

I agree. A very common annoyance in Python is the rule that you 
have to use either tabs or spaces. This is a major annoyance when 
you open a Python file in a text editor that inserts tabs or 
spaces automatically. This has happened on countless occasions 
and it's a trivial issue that detracts your attention from 
writing code. In Python you spend a lot of time just formatting 
code instead of writing it. Thus, you're not really more 
efficient in Python. Now, you might say that a good tool should 
fix this, but a) fixing things with a tool takes time as well, b) 
tools might not always be able to tell what your intention was 
[1], and c) if you need a lot of tools to write even simple code, 
there's something wrong with the language's design.

As has been said before, Python is not meant to do what D does. 
Python's rigid syntax rules are purely pedagogical, to avoid that 
non-programmers make a mess of the source code (as would happen 
with Perl). Someone who uses D is usually enough into programming 
(or willing enough to learn it) to be able to deal with curly 
braces and semicolons. Although not obvious from looking at 
Python one or two liners, braces and semicolons are valuable 
features (or tools) whose usefulness only comes apparent once you 
dig deeper and get into more complicated stuff. Python is a 
different beast and for Python it's fine to have no curly braces 
and semicolons. However, the problem is that Python became bigger 
and bigger and left it's cosy realm of scripting in labs, was 
used for bigger projects and actually became quite popular. 
People inferred from this that PLs don't need curly braces and 
semicolons. Yet Rob Pike's decision to use curly braces in Go is 
a good example of the hidden dangers of an overly simplistic 
syntax. It didn't scale.

[1] Consider the following code, which will work correctly:

x = 5

if x < 6:
   print "Checking value"
   print "%d is less than 6" % x

Now look at this:

x = 10

if x < 6:
   print "Checking value"
print "%d is less than 6" % x  # <--- wrong indentation level

This will incorrectly print "10 is less than 6". Which gives 
causes two problems

1. no compiler or editing tool can see what your intention was
2. the program works, albeit, incorrectly. In bigger programs, it 
can take a while to find out why the program is behaving 
incorrectly, because up to 5 it always works fine, and if 6-10 is 
less common, it can take a while until you even notice the bug.

In D (or C) it doesn't matter:

if (x < 6)
{
   writeln("Checking value");
writefln("%d is less than 6", x);
}