If any of you have written code in the last year that had an explicit loop […], you don’t understand collections. David West.

see also

• Ruby vs Python comes down to the for loop / HN - Ruby inherits it’s approach to flow control from Smalltalk, while Python comes from a C/Algol-like heritage.
  • HN - Once you implement each, include Enumerable is all it takes to get the full set of collection methods (including max/min etc, if the entries define <=>).
• No Stinking Loops - The K language provides constructs like each, over, and scan to perform what would be looping behavior in other languages.

see also Enumerable

• none?, any?, one?, all?
• include?
• min_by, max_by, sort_by
• filter, reject, select

As a side note…

negative loop in ruby

range 10..1 is not usable

for i in 10.downto 0
  puts i
end

or

10.step(0, -1){ |i| puts i}

or

10.downto 0 do |i|
  puts i
end

Natural forward loop

for i in 1..10
  ...
end

Iterate on string

"input".each_char { |c| ... }
"input".chars.map { |c| ... }
"input".chars.each_with_index { |c,i| ... }
"input".bytes     { |c| ... }

Send method to each object in Array

array.each(&:some_method)
# Which is shorthand for
array.each(&Proc.new { |x| x.some_method })
# Use that version if you need to pass parameters to the method.