.rb

#!/usr/bin/env ruby

class MegaGreeter
  attr_accessor :names

  def initialize(names = 'World')
    @names = names
  end

  def say_hi
    if @names.nil?
      puts '...'
    elsif @names.respond_to? :each
      @names.each do |name|
        puts "hello #{name}"
      end
    else
      puts "hello #{@names}"
    end
  end
end

def fib(n)
  return 0 if n.zero?
  return 1 if n < 2

  fib(n - 1) + fib(n - 2)
end

def min_max_sum(arr)
  [arr.sum - arr.max, arr.sum - arr.min]
end

def merge_sorted(arr1, arr2)
  result = []

  while !arr1.length.zero? && !arr2.length.zero?
    if arr1[0] < arr2[0]
      result.push arr1.shift
    else
      result.push arr2.shift
    end
  end

  result.concat arr1, arr2
end

def merge_sort(arr)
  return arr if arr.length < 2

  merge_sorted(merge_sort(arr[0, arr.length / 2]),
               merge_sort(arr.drop(arr.length / 2)))
end

puts merge_sort([2, 3, 1, 5, 1, 22, 11])

def curry(func, *args)
  lambda do |*new_args|
    args = args.concat new_args
    if args.length == func.arity
      func.call(*args)
    else
      curry func, args
    end
  end
end

def a(b, c)
  puts b, c
end

puts curry(method(:a)).call(1).call.call(2)

https://gist.github.com/scdekov/ccf587f2a5ee2943278818e2e70df51e#file-rb-L60 I would go for one-liner here

args.length == func.arity ? func.call(*args) : curry(func, args)

and also be consistent when using brackets. Better use brackets at most of the places except some simple one as:

puts "some string"

https://gist.github.com/scdekov/ccf587f2a5ee2943278818e2e70df51e#file-rb-L34 better naming than arr1, arr2. Maybe left_arr and right_arr will be better.

I'm concern about mutating args here https://gist.github.com/scdekov/ccf587f2a5ee2943278818e2e70df51e#file-rb-L57. It may not a problem in this situation but using concat with some data that have come from outside isn't a good practice(mutation).

You can use modules as containers for functions.

module M
  def self.baba
    # something
  end
end

M.baba