a = (0..100).to_a
 
a.all? do |x|
  !(x == 1000)
end
 
nil == a.index do |x|
  x == 1000
end

除了第二个一直快一点.为什么？

user     system      total        real
testing all                      1.140000   0.000000   1.140000 (  1.144535)
testing index                    0.770000   0.000000   0.770000 (  0.769195)