the value of is known only at runtime, a two-stage power function can be used in MetaOCaml: let rec power n x = if n = 0 then .<1>. else if even n then sqr (power (n/2) x) else .<.~x *. .~(power (n - 1) x)>. As soon as is known at runtime, a specialized and very fast power function can be created: .<fun x -> .~(power 5 .<x>.)>. The result is: fun x_1 -> (x_1 * let y_3 = let y_2 = (x_1 * 1) in (y_2 * y_2) in (y_3 * y_3)) The new function is automatically compiled. Other derived languages AtomCaml provides a synchronization primitive for atomic (transactional) execution of code. Emily (2006) is a subset of OCaml 3.08 that uses a design rule verifier to enforce object-capability model security principles. F# is a .NET Framework language based on OCaml. Fresh OCaml facilitates manipulating names and binders. GCaml adds extensional polymorphism to OCaml, thus allowing overloading and type-safe marshalling. JoCaml integrates constructions for developing concurrent and distributed programs. OCamlDuce extends OCaml with features such as XML expressions and regular-expression types. OCamlP3l is a parallel programming system based on OCaml and the P3L language. Reason is an alternative OCaml syntax and toolchain for OCaml created at Facebook, which can compile to both native code and JavaScript. ReScript is a rebranding and new language from the Reason/BuckleScript toolchain, which has different syntax and only compiles to JavaScript. Software written in OCaml 0install, a multi-platform package manager. CamlPDF, an OCaml library for reading, writing and modifying PDF files Coccinelle, a utility for transforming the source code of C programs. Coq, a formal proof management system. FFTW, a library for computing discrete Fourier transforms. Several C routines have been generated by an OCaml program named . The web version of Facebook Messenger. Flow, a static analyzer created at Facebook that infers and checks static types for JavaScript. Owl Scientific Computing, a dedicated system for scientific and engineering computing. Frama-C, a framework for analyzing C programs. GeneWeb, free and open-source multi-platform genealogy software. The Hack programming language compiler, created at Facebook, extending PHP with static types. The Haxe programming language compiler. HOL Light, a formal proof assistant. Infer, a static analyzer created at Facebook for Java, C, C++, and Objective-C, used to detect bugs in iOS and Android apps. Lexifi Apropos, a system for modeling complex derivatives. MirageOS, a unikernel programming framework