[kbenson]

Ruby (and Python) likely get that from Perl, which has post conditionals, but with specific qualities to prevent them from too much abuse, and which also prevents them from being used in the way presented here (which is why I didn't trot them out earlier, as much as I was tempted by the "you write what you mean" line). The limitations are that there is no else branch, and it only applies to a single statement, so you can't have a block executed with a post conditional. It leads to usage like so:

    die "Invalid param: please enter a positive number" unless $param1 > 0;
    
    $param2 = 0 unless defined $param2;

    return undef if $param1 and not $param2;
    
    my $foo = 1 if $bar; # This unfortunately creates a closure around $foo and is a big source of bugs.

As much flak as Perl gets, quite a lot of thought went into making it flow similar to how people think and talk (which is no surprise if you know Larry Wall is a linguist by training). There were some missteps, but it was very early in this area, so that's expected.

[cutler]

Perl hung onto too many of its warts for too long to stand a chance of competing with Ruby and Python. Only recently has Perl5 introduced real function parameters instead of unrolling @. Flattened lists are another one but the worst is having to specify "use 5.020;" if I'm using Perl 5.20. They've even carried this "tradition" into Perl6 where you have to specify "use v6;" at the top of EVERY damned script. That's progress? Prefixing every variable with "my" is another one which found its way into Perl6. Why can't an advanced language have default lexical scope?

[kbenson]

> Only recently has Perl5 introduced real function parameters instead of unrolling @.

Yet there have been modules that support it for years, and with much more features than what was recently rolled out (which was meant to be conservative).

Here's[1] what I said about this quite a while ago. Named parameters with type checking (unfortunately at runtime). I've been writing Perl using different modules (Function Parameters) which use the same syntax for about six years now (for functions, not all the sugar on Moose objects).

> Flattened lists are another one

Flattened lists never cause me a problem. If they cause someone problems, I think they've never really learned what context is in Perl. Once you know how context works in Perl and had a chance to use it to good effect, I can't imagine this complaint persisting. Perl is fundamentally different than most languages in this respect, even if it looks superficially similar to more procedural languages. This is actually a cause of a lot of problems for novice users, because they assume their experience in C/Algol derivatives will map exactly, and where it doesn't people get frustrated.

> but the worst is having to specify "use 5.020;" if I'm using Perl 5.20

What? You don't have to do that. If you want to use newer features that utilize keywords which may conflict with whatever you've written or whatever modules you are using, then yet, you need to opt into those. Perhaps you would have preferred if it silently just broke?

> They've even carried this "tradition" into Perl6 where you have to specify "use v6;" at the top of EVERY damned script.

No, you don't. If you do, and you run it in Perl 5, it will automatically swap out the interpreter for whatever Perl 6 interpreter you have in $PATH though.

> Prefixing every variable with "my" is another one which found its way into Perl6. Why can't an advanced language have default lexical scope?

The requirement to define your variables is not because it's not lexical by default (it is lexical by default, you can use no strict to see). .It's strictness which is enforced, which has been found by the Perl community to be vastly preferably to automatic instantiation of variables because it prevents bugs, and prevents a lot of confusion. You have to define your variable, because the Perl community found that a more sane default.

1: https://news.ycombinator.com/item?id=11633961