Uestion about ruby continuations

Hi guys, I was playing with continuations in Scheme and decided to
port one puzzle from scheme to ruby. But it works in a different way.

Here is my code and explatations:

Can someone explain why is this happening?
Are there some limitations on how continuations can be used in ruby?

Hi Max Gonzih,


lambda do |yin, yang|
yin.call yang
end.call(lambda {|cc| print “@”; cc }.call(callcc { |c| c } ),
lambda {|cc| print “*”; cc }.call(callcc { |c| c } ) )

The path was:

  1. A good explanation of the algorithm over here:
  2. An explanation of Scheme “let” here:


Let is only syntactic sugar for an underlying lambda application:

((lambda (var1 var2 … varn)
exp1 exp2 … expn)

And this made it easy for me to translate the algorithm into Ruby.

Best Regards,
Abinoam Jr.

PS: Run the “debug” version bellow and you will be able to see it “in

“Debug” version

lambda do |yin, yang|
yin.call yang
end.call(lambda {|cc| print “@ - #{cc}\n”; sleep 0.1; cc }.call(callcc
{ |c| c } ),
lambda {|cc| print “* - #{cc}\n”; sleep 0.1; cc }.call(callcc
{ |c| c } ) )

Abinoam Jr.

Now I get it. Great job, thank you!

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