00106 template<typename _InputIterator, typename _Tp, typename _BinaryOperation> 00107 _Tp 00108 accumulate(_InputIterator __first, _InputIter

00106 template<typename _InputIterator, typename _Tp, typename _BinaryOperation> 00107 _Tp 00108 accumulate(_InputIterator __first, _InputIterator __last, _Tp __init, 00109 _BinaryOperation __binary_op) 00110 { 00111 // concept requirements 00112 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 00113 __glibcxx_requires_valid_range(__first, __last); 00114 00115 for (; __first != __last; ++__first) 00116 __init = __binary_op(__init, *__first); 00117 return __init; 00118 } https://gcc.gnu.org/onlinedocs/libstdc++/libstdc++-html-USERS-4.0/stl__numeric_8h-source.html#l00108 It's just a loop. The compiler is doing all of the same transformations regardless of whether you use the higher order function or just write a loop yourself. -------------- _STD_BEGIN _EXPORT_STD template <class _InIt, class _Ty, class _Fn> _NODISCARD _CONSTEXPR20 _Ty accumulate(const _InIt _First, const _InIt _Last, _Ty _Val, _Fn _Reduce_op) { // return noncommutative and nonassociative reduction of _Val and all in [_First, _Last), using _Reduce_op _STD _Adl_verify_range(_First, _Last); auto _UFirst = _STD _Get_unwrapped(_First); const auto _ULast = _STD _Get_unwrapped(_Last); for (; _UFirst != _ULast; ++_UFirst) { #if _HAS_CXX20 _Val = _Reduce_op(_STD move(_Val), *_UFirst); #else // ^^^ _HAS_CXX20 / !_HAS_CXX20 vvv _Val = _Reduce_op(_Val, *_UFirst); #endif // ^^^ !_HAS_CXX20 ^^^ } return _Val; } https://github.com/microsoft/STL/blob/63354c3fa9c1fb2ab1fccb58c47d23c6af1c290f/stl/inc/numeric#L24 Also just a loop in MS' standard lib.