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Anonymous recursion: Difference between revisions
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→{{header|Python}}
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=={{header|Python}}==
<lang python>>>> Y = lambda f: (lambda x: x(x))(lambda y: f(lambda *args: y(y)(*args)))▼
▲>>> Y = lambda f: (lambda x: x(x))(lambda y: f(lambda *args: y(y)(*args)))
>>> fib = lambda f: lambda n: None if n < 0 else (0 if n == 0 else (1 if n == 1 else f(n-1) + f(n-2)))
>>> [ Y(fib)(i) for i in range(-2, 10) ]
[None, None, 0, 1, 1, 2, 3, 5, 8, 13, 21, 34]</lang>
Same thing as the above, but modified so that the function is uncurried:
<lang python>>>> Y = lambda f: (lambda x: x(x))(lambda y: lambda *args: f(y(y), *args))
>>> fib = lambda f, n: None if n < 0 else (0 if n == 0 else (1 if n == 1 else f(n-1) + f(n-2)))
>>> [ Y(fib)(i) for i in range(-2, 10) ]
[None, None, 0, 1, 1, 2, 3, 5, 8, 13, 21, 34]</lang>
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