The Joy of Perl (1998)

Post by zbentley » Sun, Dec 22, 2019, 2:21 AM UTC

jlokier wrote: post #46

ben509 wrote: post #39

Earlier quoted context omitted.

It's incredibly confusing if you naively use a list as a default argument, e.g. def foo(some_list=[]): ... some_list.append(3) ... Since the default is constructed when the function is evaluated, it's the same list, but only when the default is used. Or the n00b's attempt to use lambdas: def list_of_lambdas(x): result = [] for n in range(x): result.append(lambda m: n + m) return result for func in list_of_lambdas(3):…

Yes indeed, that's a bug-prone misfeature of Python. Perl and JavaScript both get default arguments right: They make a new array on each call. Perl and JavaScript also get the for-loop closures right as well. In Perl, "for (my $n = ...)" and in JavaScript "for (let n = ...)" will both create a new "cell" each time around the loop, so closures work as expected. (However, MSIE's version of "let" doesn't create a new "c…

Post by lloeki » Sun, Dec 22, 2019, 8:47 AM UTC

pflanze wrote: post #59

wwarner wrote: post #55

The thing about perl I still miss is the metaprogramming. It's really amazing to be able to launch a program that writes the "last mile" of code before it starts taking requests.

You can do a lot in Perl with just closures and setting package slots etc., that you would need to use macros for in say Lisps. Still, I agree, there's no real AST and string eval is unsafe and parsing is a real issue. I've started https://metacpan.org/pod/FP::AST::Perl (very unfinished) to solve the code generation issue and hope to generate an AST from the op tree (not sure how feasible, will see). Feel free to tel…

Post by jlokier » Sun, Dec 22, 2019, 9:21 AM UTC

zbentley wrote: post #61

jlokier wrote: post #46

Earlier quoted context omitted.

Yes indeed, that's a bug-prone misfeature of Python. Perl and JavaScript both get default arguments right: They make a new array on each call. Perl and JavaScript also get the for-loop closures right as well. In Perl, "for (my $n = ...)" and in JavaScript "for (let n = ...)" will both create a new "cell" each time around the loop, so closures work as expected. (However, MSIE's version of "let" doesn't create a new "c…

Perl has default arguments (outside of Devel::Declare trickery)?

  use experimental qw(signatures);

  sub plus_one($x = 100) {
      return $x + 1;
  }

  # Says 6.
  say plus_one(5);

  # Says 101.
  say plus_one();

Post by lizmat » Sun, Dec 22, 2019, 12:18 PM UTC

jlg23 wrote: post #66

lizmat wrote: post #58

Earlier quoted context omitted.

Did Duke Nukem Forever change its name? Perl 6 has. It's called Raku now ( https://raku.org using the #rakulang tag on social media). And it is very much alive and ready for production.

No, but it was so long in the making that I had discovered alternatives and mastered them. I still write perl5 sometimes but none of perl6 features convinced me to install an interpreter anywhere when I already have ruby or python on the machine.

Post by scarface74 » Sun, Dec 22, 2019, 1:20 PM UTC

petre wrote: post #64

scarface74 wrote: post #26

Earlier quoted context omitted.

Until you need your next job and you see spending 10 years doing Perl was detrimental to your career...

At least it's fun to write modern Perl code compared to Js which is kind of annoying. Raku is also a very nice language but it's still too slow and hasn't gained much traction. Someone who's proficient in Perl can probably become productive in Python in less than a month.