Back to Basics Lambda Expressions Barbara Geller & Ansel Sermersheim CppCon September 2020Introduction ● Prologue ● History ● Function Pointer ● Function Object ● Definition of a Lambda Expression slot library ○ CsLibGuarded ■ library for managing access to data shared between threadsLambda Expressions ● History ○ lambda calculus is a branch of mathematics ■ introduced in the 1930’s to prove memory ■ languages which were influenced by lambda calculus ● Haskell, LISP, and ML 5Lambda Expressions ● History ○ why do we use the terminology lambda expression ■ greek letter λ refers to an anonymous

About me 2 6 ways for implementing math expressions calculator, Amir Kirsh Lecturer Academic College of Tel-Aviv-Yaffo and Tel-Aviv University Developer Advocate at Member of the Israeli ISO C++ NB NB Co-Organizer of the CoreCpp conference and meetup group3 6 ways for implementing math expressions calculator, Amir Kirsh Suffering from slow builds? It’s not just waste of time It affects your dev implementing math expressions calculator, Amir KirshSuccess Stories 5 6 ways for implementing math expressions calculator, Amir KirshSuccess Stories 6 6 ways for implementing math expressions calculator, Amir

Object Parameters  if consteval  Multidimensional Subscript Operator  Attributes on Lambda-Expressions  Literal Suffix for size_t  auto(x): decay-copy in The Language  #elifdef, #elifndef, and Object Parameters  if consteval  Multidimensional Subscript Operator  Attributes on Lambda-Expressions  Literal Suffix for size_t  auto(x): decay-copy in The Language  #elifdef, #elifndef, and std::forward(self).m_name; }11 Explicit Object Parameters  Allows for recursive lambda expressions  this in a lambda accesses the object that contains the lambda, not the lambda instance itself

same time, a lot of enhancements 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 concept of constant expressions, such as 1+2, 3*4. Such expressions always produce the same result without any side effects. If the compiler can directly optimize and embed these expressions into the program beginning of this chapter, we know that C++11 introduces the constexpr keyword, which compiles expressions or functions into constant results. A natural idea is that if we introduce this feature into the

Machine 26 • Implementations must emulate the observable behavior of the abstract machine • Expressions with non-observable side effects may be ignoredCopyright © 2020 Bob Steagall K E W B C O M P Machine 28 • Implementations must emulate the observable behavior of the abstract machine • Expressions with non-observable side effects may be ignoredCopyright © 2020 Bob Steagall K E W B C O M P Machine 30 • Implementations must emulate the observable behavior of the abstract machine • Expressions with non-observable side effects may be ignoredCopyright © 2020 Bob Steagall K E W B C O M P

digits. However, your character class range `a--z` seems to be incorrectly typed. In regular expressions, a single `-` is used to represent a range, so this should be `a-z` instead: So the corrected the code should compile without issues. This kind of messages can help you debug your regular expressions in the future by helping you locate problematic parts of your regular expression. So when you digits. However, your character class range `a--z` seems to be incorrectly typed. In regular expressions, a single `-` is used to represent a range, so this should be `a-z` instead: So the corrected

ce, fieldDecl( hasType(asString("int"))))AST Matcher Reference 56AST Matchers - Matcher Expressions Looking for calls to a member function on a class named A and whose called function is named callee(functionDecl( hasName(“foo”), hasParameter(0, hasType(isInteger())))))AST Matchers - Matcher Expressions Looking for calls to a member function on a class named A and whose called function is named callee(functionDecl( hasName(“foo”), hasParameter(0, hasType(isInteger())))))AST Matchers - Matcher Expressions Looking for calls to a member function on a class named A and whose called function is named

Comparison Binding Constraints Architecture Substitution Construction Conclusion Mathematical expressions Normal distribution PDF f = 1 √ 2πσ2 e− (x−µ)2 2σ2 2 + + 2 Normal distribution Legend Function Architecture Substitution Construction Conclusion Concepts: the constructions (expressions) y(t) = a × sin (ω × t + ϕ) Symbolic expressions term: “a mathematical object”: ϕ, ω, ω × t + ϕ, . . . formula: “a mathematical value to a symbolic variable substitution: replacing symbolic variables by their values in an expressions rewriting: replacing subterms by other terms in formulas CppCon - Vincent Reverdy - October 4th

lukevalenty (Luke Valenty) Assigned to: elbeno (Ben Deane) Factor arbitrary matcher expressions into "sum-of-products" expressions https://github.com/intel/compile-time-init-build 7Part 1 Fields and messages: something */ }); 30Boolean algebra primer/refresher In upcoming slides you'll see some Boolean expressions (not necessarily in C++). Just so we're all clear, I'm using this convention: ∧ means and: A simple as possible. 32Example matcher problems We've made it easy for people to write complex expressions, possibly containing tautologies or contradictions, or at least common parts… How does the library

Coroutines  Concepts  Lambda Expression Changes  [=, this] as Lambda Capture  Templated Lambda Expressions  Pack Expansion in Lambda Captures  constexpr Changes  virtual functions  union, try/catch C++20, you need to be explicit, so: [=, this]27 Templated Lambda Expressions  Use familiar template syntax with lambda expressions [] (T x) { /* ... */ } [] (T* p) { /* . .. */ } [] (T (&a)[N]) { /* ... */ }28 Templated Lambda Expressions  Motivation 1  Generic lambda accepting a vector; you want to know T (pre C++20): [](const auto& vec) {