25 lines
724 B
Hy
Executable File
25 lines
724 B
Hy
Executable File
#!/usr/bin/env hy
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; Very much a knockoff (straight port) of Dan Gulotta's 2013 MIT Mystery Hunt
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; puzzle "The Halting Problem". His Copyright terms are unclear, so presume
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; that this is distributable, but not free.
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(defn evaluate [f] ((f (lambda [x] (+ x 1))) 0))
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(defn successor [n] (lambda [f] (lambda [x] (f ((n f) x)))))
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(defn plus [m n] ((n successor) m))
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(defn exponent [m n] (n m))
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(defn zero [f] (lambda [x] x))
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(defn one [f] (lambda [x] (f x)))
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(defn predecessor [n] (lambda [f] (lambda [x]
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(((n (lambda [g] (lambda [h] (h (g f))))) (lambda [y] x)) (lambda [z] z)))))
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(defn subtract [m n] ((m predecessor) n))
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(def two (plus one one))
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(def three (plus two one))
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(print (evaluate (exponent three three)))
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