c++实现类似Common Lisp的多参数加法和比较

1 $ sbcl
2 * (+ 1 2 3)
3 6
4 * (< 1 2 3)
5 T
6 * (< 2 3 1)
7 NIL
8 * 

 1 #include <functional>
 2 template<typename O, typename A,typename B>
 3 bool cmp(O o, A a,B b){
 4     return o(a, b);
 5 }
 6 template<typename O, typename A,typename B,typename... C>
 7 bool cmp(O o,A a,B b,C... c){
 8     return o(a, b) and cmp(o,b,c...);
 9 }
10 template<typename O, typename A,typename B>
11 A reduce(O o, A a,B b){
12     return o(a, b);
13 }
14 template<typename O, typename A,typename B,typename... C>
15 A reduce(O o,A a,B b,C... c){
16     return reduce(o,o(a, b),c...);
17 }
18 
19 bool foo(int a,int b,int c,int d){
20   return cmp(std::less<int>(), a,b,c,d);
21 }
22 int bar(int a,int b,int c,int d){
23   return reduce(std::plus<int>(), a,b,c,d);
24 }

 1 foo(int, int, int, int):                             # @foo(int, int, int, int)
 2     cmpl    %esi, %edi
 3     jge    .LBB0_1
 4     cmpl    %edx, %esi
 5     setl    %sil
 6     cmpl    %ecx, %edx
 7     setl    %al
 8     andb    %sil, %al
 9     ret
10 .LBB0_1:
11     xorl    %eax, %eax
12     ret
13 
14 bar(int, int, int, int):                             # @bar(int, int, int, int)
15     addl    %esi, %edi
16     leal    (%rdi,%rdx), %eax
17     addl    %ecx, %eax
18     ret