44 lines
1.4 KiB
C#
44 lines
1.4 KiB
C#
using System;
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using System.Diagnostics;
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static class Program {
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delegate TResult ParamsFunc<T, TResult>(params T[] args);
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static class Y<Result, Args> {
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class RecursiveFunction {
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public Func<RecursiveFunction, ParamsFunc<Args, Result>> o;
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public RecursiveFunction(Func<RecursiveFunction, ParamsFunc<Args, Result>> o) => this.o = o;
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}
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public static ParamsFunc<Args, Result> y1(
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Func<ParamsFunc<Args, Result>, ParamsFunc<Args, Result>> f) {
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var r = new RecursiveFunction(w => f(args => w.o(w)(args)));
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return r.o(r);
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}
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}
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static ParamsFunc<Args, Result> y2<Args, Result>(
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Func<ParamsFunc<Args, Result>, ParamsFunc<Args, Result>> f) {
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Func<dynamic, ParamsFunc<Args, Result>> r = w => {
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Debug.Assert(w is Func<dynamic, ParamsFunc<Args, Result>>);
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return f(args => w(w)(args));
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};
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return r(r);
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}
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static ParamsFunc<Args, Result> y3<Args, Result>(
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Func<ParamsFunc<Args, Result>, ParamsFunc<Args, Result>> f)
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=> args => f(y3(f))(args);
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static void Main() {
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var factorialY1 = Y<int, int>.y1(fact => x => (x[0] > 1) ? x[0] * fact(x[0] - 1) : 1);
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var fibY1 = Y<int, int>.y1(fib => x => (x[0] > 2) ? fib(x[0] - 1) + fib(x[0] - 2) : 2);
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Console.WriteLine(factorialY1(10));
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Console.WriteLine(fibY1(10));
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}
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}
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