24 lines
764 B
Java
24 lines
764 B
Java
import java.util.function.Function;
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public class YCombinator {
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interface RecursiveFunc<F> extends Function<RecursiveFunc<F>, F> { }
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public static <A,B> Function<A,B> fix(Function<Function<A,B>, Function<A,B>> f) {
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RecursiveFunc<Function<A,B>> r = w -> f.apply(x -> w.apply(w).apply(x));
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return r.apply(r);
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}
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public static void main(String[] args) {
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Function<Integer,Integer> fib = fix(f -> n -> {
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if (n <= 2) return 1;
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return f.apply(n - 1) + f.apply(n - 2);
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});
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Function<Integer,Integer> fac = fix(f -> n -> {
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if (n <= 1) return 1;
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return n * f.apply(n - 1);
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});
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System.out.println("fib(10) = " + fib.apply(10));
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System.out.println("fac(10) = " + fac.apply(10));
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}
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}
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