如何使用 Ruby 的新 lambda 语法？

Ruby 有 lambda 语法，所以我可以使用-> symbol:

a = 0
new  -> { a < 5 }  do
   puts a
   a += 1
end

这非常有效，但是当我尝试这样做时：

match "/", to:  -> { |e| [404, {}, ["Hello! I am micro rack app"]] }, via: [:get]
match( "/", to:  -> { |e| [404, {}, ["Hello! I am micro rack app"]] }, via: [:get] )
match( "/", { to:  -> { |e| [404, {}, ["Hello! I am micro rack app"]] }, via: [:get] })

所有返回相同的语法错误：

$ ruby -c -e 'match( "/", to:  -> { |e| [404, {}, ["Hello! I am micro rack app"]] }, via: [:get] )'
-e:1: syntax error, unexpected '|'
match( "/", to:  -> { |e| [404, {}, ["Hello! I am mi...

我错过了什么吗？

我认为新的语法应该是

match "/", to:  ->(e) { [404, {}, ["Hello! I am micro rack app"]] }, via: [:get]