Why do Ruby's default parameter values not get assigned to nil arguments?

I'm new to Ruby and came across something that confused me a bit. I set a default parameter value in a method signature. When calling the method, I passed a `nil` argument to that parameter. But the default value wasn't assigned; it remained `nil`. ``` # method with a default value of 1000 for parameter 'b' def format_args(a, b=1000) "\t #{a.ljust(30,'.')} #{b}" end # test hash dudes = {}; dudes["larry"] = 60 dudes["moe"] = nil # expecting default parameter value puts "Without nil check:" dudes.each do |k,v| puts format_args(k,v) end # forcing default parameter value puts "With nil check:" dudes.each do |k,v| if v puts format_args(k,v) else puts format_args(k) end end ``` Output: ``` Without nil check: larry......................... 60 moe........................... With nil check: larry......................... 60 moe........................... 1000 ``` Is this expected behavior? What ruby-foo am I missing? Seems like `nil` isn't the same "no value" that I'm accustomed to thinking of `null` in other languages.