20-CS-4003-001 |
Organization of Programming Languages |
Fall 2017 |
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Lambda |

**Lambda - Y Combinator**

(((lambda (procedure) (lambda (n) (if (zero? n) 1 (* n ((procedure procedure) (- n 1)))))) (lambda (procedure) (lambda (n) (if (zero? n) 1 (* n ((procedure procedure) (- n 1))))))) 5) |
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Consider the code to the left. This produces the factorial of 5
because the procedure which is invoked (the huge mess) is exactly the
definition of "fact." But, lo and behold, there is no name for this
procedure anywhere!
In what follows, we try to generalize this to all procedures of one argument and wind up with the applicative-order Y-combinator. |
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