Hacker News Reader

Hacker News

Comment by muyyatin | Hacker News Reader

Parent Full thread

muyyatin

In Scala you can just do:

employees.filter( _.isPartTime )

And it runs in the same virtual machine.

View on HN

Joining the club, in Python:

[e for e in employees if e.isPartTime()]

You can even push it further:

[e for e in employees if e.isPartTime() or e.lazy() or e.havePassiveIncomeAlready()]

and further:

[e for e in employees if e.isPartTime() or e.lazy() or e.havePassiveIncomeAlready() or e in [exec for exec in BoardofDirector.all() if exec.haveTooManyPortfolio()]]

Above is your friendly neighborhood List Comprehension available since Jython 2.0

In Ruby:

employees.find_all &:isPartTime

And I liked employees.select {|employee| employee.part_time?}

Crikey, should buy a book...

Personally, I prefer your version; the &: version starts reeking of Perl line noise. Although I believe Ruby would benefit from an _ for not explicitly named block arguments.

As a random note for anyone who's wondering how this syntax came about, this is the Symbol#to_proc [1] method, which was actually a monkeypatch from Rails that ended up making its way back into Ruby proper.

1: http://ruby-doc.org/core-1.9/classes/Symbol.html#M000031

I agree, I also prefer the slightly longer version. OK, enough small talk ... :-)

Thank goodness Symbol#to_proc was introduced in Ruby 1.9, the Rails implementation of it was slow as hell: http://www.lukeredpath.co.uk/blog/optimising-symbol-to_proc....

That was fixed some time ago. It is very marginally slower to use Symbol#to_proc now (a constant time difference to actually create the Proc), but not enough to warrant a change in practical use.

Yeah, that improved java is still pretty ugly for a JVM language. In groovy its:

employees.findAll { it.isPartTime() }

And in clojure it would be

    (filter :part-time? employees)

Reply on news.ycombinator.com