Single- vs multiline lambdas

The style guide currently says

Use the new lambda literal syntax for single line body blocks. Use the lambda method for multi-line blocks. [link]

# bad
l = lambda { |a, b| a + b }
l.call(1, 2)

# correct, but looks extremely awkward
l = ->(a, b) do
  tmp = a * 7
  tmp * b / 50
end

# good
l = ->(a, b) { a + b }
l.call(1, 2)

l = lambda do |a, b|
  tmp = a * 7
  tmp * b / 50
end

I disagree. Having to change lambda syntax from -> {} to lambda do; end when a lambda grows too large for one line seems wrong. For multi-line lambdas, I would prefer using the stabby lambda syntax with a curly-brace block:

# good
l = ->(a, b) {
  tmp = a * 7
  tmp * b / 50
}

Start by reading the current style-guide guidance quoted in the issue and the nine-comment discussion to understand the unresolved positions. Done means reaching a decision on multiline stabby-lambda syntax and updating the relevant guidance and examples consistently.