gistfile1.txt

Code:
def count_words(str)
  counter = Hash.new {|h,k| h[k] = 0}
  str.split(/\b/).each {|word| counter[word.downcase]}
end

puts count_words("A guy, a girl, a canal")
#{'a' => 3, 'guy' => 1, 'girl' => 1, 'canal' => 1 }

After execution:
A
 
guy
, 
a
 
girl
, 
a
 
canal