because that's FUD

"First class object" aka citizen basically means you can pass functions around as arguments to other functions. E.G. most BASIC dialects I've seen couldn't do that.

It's a necessity for functional programming...

Perl is actually better in functional programming, since Python is restricting lambdas to one expressions only, while anonymous subs are free.

And Python doesn't offer any block prototype to make it even easier like sub foo (&) { $code = shift; ... }

Superficial people will claim that the need to explicitly reference named subs in Perl with ...

\&foo

means they are not first class.

Superficially so because almost everything in Python is implicitly a reference.

Now, who said explicit is better than implicit again ...???

because that's FUD

Huh .. too bad. I dealt with FUD with Microsoft continually slamming OS/2 in the late 80's, where we slagged Windows NT on the Canopus form on Compuserve. Good times.

I developed code in C before moving to Perl in the late 90's, and was advanced enough that I was comfortable using function pointers in my code .. so when I wanted to do the same thing Perl, it was there already. Perfect, because being able to declare a callback function (one example of a function pointer) is extremely handy.

And I don't really care what the TIOBE results say .. if a CTO contacts me to say 'Perl developers are really hard to find' and 'Are you available?', I don't find the burning need to go learn a different language. And, of course, the Perl community has been very supportive and welcoming. So I'm not going anywhere anyway. :)

Alex / talexb / Toronto

Thanks PJ. We owe you so much. Groklaw -- RIP -- 2003 to 2013.

Hmm ... I don't know C's pointer arithmetic sufficiently well, but I wouldn't call this functional programming, so callbacks alone are not enough.

For instance, can you write a generator function which returns an iterator function?

What about closures?

So probably are First class citizen a prerequisite for FP but not the whole picture.

update

here we go: Some authors require it be possible to create new functions at runtime to call them 'first-class'. As a result, functions in C are not first-class objects; instead, they are sometimes called second-class objects, because they can still be manipulated in most of the above fashions (via function pointers).

see also First class functions

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery}

Finally, I must also point out. A lot of times it's okay to use bash. I maintain a mix of Perl and bash scripts; your tolerance and own needs will guide you where the "line" for that decision is.

Which is good for "code reuse"

Doing

package Modulino;
sub main { }
caller() ? 1 : main;
[download]

perl "$( perldoc -lm Modulino )"
[download]

is not better for code reuse over the traditional

package Modulino;
sub main { }
1
[download]

perl -MModulino -emain
[download]