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#include <iostream>
#include <functional>
#include <list>
using namespace std;
 
 
template <typename R, typename... Arg>
    function<R (Arg...)> decor(
        initializer_list<
            function<function<R (Arg...)> (function<R (Arg...)>)>
        > transformers,
        function<R (Arg...)>&& func) 
    {
        list<function<function<R (Arg...)> (function<R (Arg...)>)>> tfs;
        tfs.assign(transformers);
        tfs.reverse();
 
        function<R (Arg...)> fn = func;
        for (auto tf : tfs) {
            fn = tf(fn);
        }
        return fn;
    }
 
template <typename F>
F add42(F fn) {
    return [=] (int x) -> int {
        return fn(x) + 42;
    };
}
 
template <typename F>
F div2(F fn) {
    return [=] (int x) -> int {
        return fn(x) / 2;  
    };
}
 
auto func = decor({add42, div2}, [=] (int x) -> int {
    return x * 2;
});
 
int main() {
    cout << "f(1) = " << func(1) << endl;
}

prog.cpp:41:2: error: no matching function for call to ‘decor(<brace-enclosed initializer list>, <lambda(int)>)’
prog.cpp:41:2: note: candidate is:
prog.cpp:8:26: note: template<class R, class ... Arg> std::function<_Res(_ArgTypes ...)> decor(std::initializer_list<std::function<std::function<_Res(_ArgTypes ...)>(std::function<_Res(_ArgTypes ...)>)> >, std::function<_Res(_ArgTypes ...)>&&)
prog.cpp:8:26: note:   template argument deduction/substitution failed:
prog.cpp:41:2: note:   ‘<lambda(int)>’ is not derived from ‘std::function<_Res(_ArgTypes ...)>’
prog.cpp:41:2: error: unable to deduce ‘auto’ from ‘<expression error>’

Standard output is empty