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  1. def combinator &b
  2.   lambda do |f|
  3.     lambda{|x|lambda{|y| f[x[x]] [y]}}[
  4.       lambda{|x|lambda{|y| f[x[x]] [y]}}]
  5.   end[ lambda{|f|lambda{|n| b[n , &f] }}]
  6. end
  7.  
  8. a = combinator do | n , &f |
  9.   if n == 0
  10.     1
  11.   else
  12.     n * f.call(n-1)
  13.   end
  14. end
  15.  
  16. p a.call 7
  17.  
  18.  
  19.  
  20. def recursion &b
  21.   f = ->*n{ b[ *n , &f ] }
  22. end 
  23.  
  24. a = recursion do |n , &rec|
  25.   if n == 0
  26.     1
  27.   else
  28.     n * rec.call(n-1)
  29.   end
  30. end
  31. p a.call 7
Success #stdin #stdout 0s 4760KB
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https://ideone.com/DlkEp
language:
Ruby (ruby 2.5.5)
created:
12 years ago
visibility:
public

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