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Re^2: Ruby vs Perl vs LISP; the killer feature lacking in Ruby

by jdporter (Canon)
on May 21, 2012 at 14:00 UTC ( #971618=note: print w/ replies, xml ) Need Help??


in reply to Re: Ruby vs Perl vs LISP; the killer feature lacking in Ruby
in thread Ruby vs Perl vs LISP; the killer feature lacking in Ruby

it restricts you to just one such parameter unless you jump through hoops even most "seasoned" Ruby developers are not aware of

Is it easy to do this in Perl? It's not possible at all, afaik.

multifoo { $_ * 2 } { foo($_) } @things;
I reckon we are the only monastery ever to have a dungeon stuffed with 16,000 zombies.


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Re^3: Ruby vs Perl vs LISP; the killer feature lacking in Ruby
by Jenda (Abbot) on May 21, 2012 at 16:26 UTC
    multifoo sub { $_ * 2}, sub { foo ($_) }, @things;
    hoopsy hoops, right?

    And now the method body:

    sub onefoo { my ($reasonably_named_sub, @params) = @_; whatever; for my $foo (tweaked @params) { $reasonably_named_sub->($foo); } } sub multifoo { my ($toDo, $filter, @params) = @_; whatever; for my $foo (grep $filter->(), tweaked @params) { $toDo->($foo); } }
    Yieieiaield anyone?

    There is a little syntactic sugar for functions (not methods) in Perl, but the difference between using the sugar and not is tiny. If I need to pass two "pieces of code" into my subroutine, I pass them, I name them and I call them the same way I would if I had just one.

    In Ruby, if your method gets a single block/closure parameter, you do not get to name the parameter, you use the ill-named statement yield and it kinda, behind the scenes, maybe, works. If you need to pass two you are, basically, screwed. But then 640KB ought to be ... I mean one block ought to be enough for anybody.

    Jenda
    Enoch was right!
    Enjoy the last years of Rome.

Re^3: Ruby vs Perl vs LISP; the killer feature lacking in Ruby
by tobyink (Abbot) on May 23, 2012 at 07:38 UTC

    As well as Jenda's suggestion, it's also possible to declare a little wrapper like this:

    sub also (&;@) { return @_; }

    Enabling you to do this:

    multifoo { $_ * 2 } also { foo($_) } @things;

    This is what Moose does for its type constraints system, providing little wrappers like via, where and message so you can write code like:

    subtype 'ModernDateTime' => as 'DateTime' => where { $_->year() >= 1980 } => message { 'The date is not modern enough' };
    perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

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