Hello
I found this to be somewhat amusing:
a =
=>
a.all?
=> true
a.all? { |i| i == 10 }
=> true
Is there any reasoning for Enumerable#all? to always return true for
empty arrays?
Best regards,
Andre
Hello
I found this to be somewhat amusing:
a =
=>
a.all?
=> true
a.all? { |i| i == 10 }
=> true
Is there any reasoning for Enumerable#all? to always return true for
empty arrays?
Best regards,
Andre
well - it's either that or false. we'd need maybe for it to really make
sense.
consider
.all?{|x| x.nil?} # true or false??
either is arbitrary
-a
On Thu, 10 Aug 2006, Andre Nathan wrote:
Hello
I found this to be somewhat amusing:
a =
=>
a.all?
=> true
a.all? { |i| i == 10 }
=> true
Is there any reasoning for Enumerable#all? to always return true for
empty arrays?Best regards,
Andre
--
to foster inner awareness, introspection, and reasoning is more efficient than
meditation and prayer.
- h.h. the 14th dali lama
Andre Nathan wrote:
Hello
I found this to be somewhat amusing:
a =
=>
a.all?
=> true
a.all? { |i| i == 10 }
=> true
Is there any reasoning for Enumerable#all? to always return true for
empty arrays?
It's what modern logic says... or something like it.
--
Andre Nathan wrote:
a =
=>
a.all?
=> true
a.all? { |i| i == 10 }
=> true
Is there any reasoning for Enumerable#all? to always return true for
empty arrays?
I think they are modeled after universal and existential quantifiers in predicate calculus:
a.all?(&b) is true iff for all x in a b.
This leads to a.all? being true.
a.any?(&b) is true iff there exists an x in a for which b.
This leads to a.any? being false.
--
Florian Frank
a.all?{ ... } == true
can be read as "All elements in a satisfy { ... }", which we can interpret as
"there is no element in a such that { ... } is not satisfied", which is
obviously true if a is empty.
On Thu, Aug 10, 2006 at 01:41:48AM +0900, Andre Nathan wrote:
Hello
I found this to be somewhat amusing:
>> a =
=>
>> a.all?
=> true
>> a.all? { |i| i == 10 }
=> trueIs there any reasoning for Enumerable#all? to always return true for
empty arrays?
--
Mauricio Fernandez - http://eigenclass.org - singular Ruby
"Andre Nathan" <andre@digirati.com.br> wrote in message
news:1155141696.24603.43.camel@andre.mz.digirati.com.br...
Hello
I found this to be somewhat amusing:
a =
=>
a.all?
=> true
a.all? { |i| i == 10 }
=> true
Is there any reasoning for Enumerable#all? to always return true for
empty arrays?
It's mathematically consistent.
You may be surprised to hear this but mathematicians are generally
optimists. Thus, if a condition is "vacuously satisfied," then we generally
say the condition is true...
OK, thank you all for the explanations
Andre
On Thu, 2006-08-10 at 03:03 +0900, Mauricio Fernandez wrote:
can be read as "All elements in a satisfy { ... }", which we can interpret as
"there is no element in a such that { ... } is not satisfied", which is
obviously true if a is empty.
unless mathematician.is_an :intuitionist # (pretty rare)
Sorry I couldn't resist
-Jürgen
On Thu, Aug 10, 2006 at 08:55:12AM +0900, Just Another Victim of the Ambient Morality wrote:
"Andre Nathan" <andre@digirati.com.br> wrote in message
news:1155141696.24603.43.camel@andre.mz.digirati.com.br...
> Hello
>
> I found this to be somewhat amusing:
>
>>> a =
> =>
>>> a.all?
> => true
>>> a.all? { |i| i == 10 }
> => true
>
> Is there any reasoning for Enumerable#all? to always return true for
> empty arrays?It's mathematically consistent.
You may be surprised to hear this but mathematicians are generally
optimists. Thus, if a condition is "vacuously satisfied," then we generally
say the condition is true...
--
The box said it requires Windows 95 or better so I installed Linux