Ruby

I have the following method:

def test(first_param = nil, keyword_arg: nil) puts "first_param: #{first_param}" puts "keyword_arg: #{keyword_arg}" end 

All the following calls do what I expect them to do:

test(:something) #=> first_param: something # keyword_arg: test(nil, keyword_arg: :keyword_arg) #=> first_param: # keyword_arg: keyword_arg test({ first_param: :is_a_hash }, keyword_arg: :is_still_working) #=> first_param: {:first_param=>:is_a_hash} # keyword_arg: is_still_working 

But omitting the optional keyword_arg and passing a hash as first argument gives me an error:

test(first_param: :is_a_hash) #=> test.rb:1:in `test': unknown keyword: first_param (ArgumentError) # from test.rb:12:in `<main>' 

I'd expect it to set first_param to { first_param: :is_hash } and keyword_arg being nil.

It seems it is interpreting every hash as keyword arg:

test(keyword_arg: :should_be_first_param) #=> first_param: # keyword_arg: should_be_first_param 

This should have set first_param to { keyword_arg: :should_be_first_param }, leaving keyword_arg nil in my opinion.

Making the first parameter mandatory and everything works like I'd expect to:

def test(first_param, keyword_arg: nil) puts "first_param: #{first_param}" puts "keyword_arg: #{keyword_arg}" end test(first_param: :is_a_hash) #=> first_param: {:first_param=>:is_a_hash} # keyword_arg: test(keyword_arg: :should_be_first_param) #=> first_param: {:keyword_arg=>:should_be_first_param} #=> keyword_arg: 

I'd expect making a parameter optional does not change the way parameters are parsed.

Is this a parser oddity or expected behaviour?