x = some_range | reversed_evens; 2 110Range Adaptor Closure Objects [24.7.2.1] A range adaptor closure object is a . For a range adaptor closure object C and an expression R such that decltype((R)) argument and returns a view C(R) R | C 111Range Adaptor Closure Objects [24.7.2.1] A range adaptor closure object is a . For a range adaptor closure object C and an expression R such that decltype((R)) and returns a view view C(R) R | C 111Range Adaptor Closure Objects [24.7.2.1] A range adaptor closure object is a . For a range adaptor closure object C and an expression R such that decltype((R))

language a bit carefully to distinguish between: a lambda expression (the code that we write) a closure object (the object the compiler generates by evaluating the lambda expression)DEDUCING this AND LAMBDAS (Despite what cppinsights tells you…)CLOSURE OBJECTS, PER THE STANDARD "An implementation may define the closure object differently…" In particular, closure objects have:CLOSURE OBJECTS, PER THE STANDARD "An implementation may define the closure object differently…" In particular, closure objects have: no defined layoutCLOSURE OBJECTS, PER THE STANDARD "An implementation may define the closure object differently…"

sample(gen) ➡ view ❌ What do we need to fix? sample(gen) ➡ C (range adaptor closure object) If C is a range adaptor closure object and R is a range, these two expressions are equivalent: C(R) R | C std::ranges::range_adaptor_closure (C++23) template class sample_closure : public std::ranges::range_adaptor_closureclosure> { public: explicit sample_closure(RNG& gen) : gen_{gen} std::ranges::range_adaptor_closure (C++23) template class sample_closure : public std::ranges::range_adaptor_closureclosure> { public: explicit sample_closure(RNG& gen) : gen_{gen}

variable name ○ a closure is simply a function object . . . ■ which is returned from the evaluation of a lambda expression ■ myLamb contains the closure ■ deduced type is a “closure data type” auto expression is evaluated ■ ensure captured lvalue references remain alive for the entire lifetime of the closure auto myLamb = [&x] ( ) { return ++x; }; 20Lambda Expressions ● Capture Clause ○ C++11 ■ capture of evaluating a lambda expression which does not capture anything as a special kind of closure ■ special closure has no state so it can be implicitly converted to a function pointer ■ if you are calling

1: // namespace maybe::views 2: 3: template 4: constexpr /* maybe adaptor closure*/ transform(Callable&& c); 01: // namespace maybe 02: 03: template 04: concept not_void maybe::views 2: 3: template 4: constexpr /* maybe adaptor closure*/ transform(Callable&& c); 1: auto closure = maybe::views::transform(f1) 2: | maybe::views::and_then(f2) 3: initialization */}; 6: auto res = closure(mbObj); // res is our or_else view 7: std::cout << "res=" << *res << std::endl; 8: 9: auto asOpt = res | maybe::to; mbobj | closure;© 2018 Bloomberg Finance

is an output side effect ● filter contains state with the variable that is initialized in the closure ○ Running filter multiple times with the same input returns different outputs ● filter_timeseries argument int result = multiplyBy2(3); std::cout << result << std::endl; // Output: 6 } ● A closure is a function object that has an environment of its own, which keeps track of the variables captured std::endl; // Output: 6 } ● A closure is a function object that has an environment of its own, which keeps track of the variables captured from the outer scope ○ A closure can access and manipulate these

have been made to the language runtime. The emergence of Lambda expressions has given C++ the “closure” feature of “anonymous functions”, which are in almost all modern programming languages (such of a class type (called a closure type) that is similar to a function object type (called a closure object). When the capture list of a Lambda expression is empty, the closure object can also be converted

member of a class? ▪ Stored in containers like queue/vector? ▪ No, because ▪ They return a Closure, and the Closure type is unique unnamed class type. ▪ Size is different based on the captures ▪ So, lambdas

concepts, imperative vs. declarative, lazy eval, monads;  Function composition and a range adaptor closure object (RACO);2. What is a pipe and a pipeline in software engineering?  Pipes in Unix/Linux;

can be used like functions ， Using operator () *，have a "unique, unnamed non-union class type" 一 "closure type [7 auto aada = (int x， int 了 1 inti = 4 eturn x 十 了 ] has the effect of class