Please make Perl autovivification possible in Ruby.

foo[obj]="hello"

(1) If foo is undefined, and if obj is not integer,
Ruby will define foo as hash like foo={}

(2) If foo is undefined, and if obj is integer,
Ruby will ** assume ** foo is array,
and  will define foo as array like foo=[]

If I want foo[5] to be hash, I have to declare foo explicitly
foo={}
foo[5]="hello"

or do it differently
foo[5.to_s]="hello"

##########
Is it possible to add C style loop to Ruby?
The following is from "Programming Ruby".

def fibUpTo(max)
  i1, i2 = 1, 1
  while i1 <= max
    yield i1
    i1, i2 = i2, i1+i2
  end
end
fibUpTo(1000) { |f| print f, " " }

C style loop:

def fibUpTo(max)
  for (i1, i2=1, 1; i1<=max; i1, i2=i2, i1+i2)
    yield i1
  end
end
fibUpTo(1000) { |f| print f, " " }

##########
Please add this cool Python stuff to Ruby.

If 25 < foo < 75 : print "middle"

It is also proposed for Perl6.

Thanks for attention.