give ruby version of this python code: `lambda s:len(s)==len({*s.lower()}-{*str(56**7)})` in ruby

In Ruby, you can convert the given Python code into the equivalent Ruby code as follows:

main.rb
def check_string_length(s)
  s.downcase.chars.uniq.length == (s.downcase.chars.uniq - (56**7).to_s.chars).length
end
117 chars
4 lines

In the above Ruby code, I have defined a method check_string_length that takes a string s as a parameter and checks if the length of the unique characters in the string is equal to the length of the string after removing the characters present in the result of (56**7).to_s. The downcase method is used to convert the string to lowercase, and chars method is used to convert the string to an array of characters.

You can call this method with a string as an argument to check if the condition is satisfied. The method will return true if the condition is met, and false otherwise.