Editing OCaml (section)

==Features==
OCaml features a [[Semantic analysis (computer science)|static]] [[type system]], [[type inference]], [[parametric polymorphism]], [[tail recursion]], [[pattern matching]], first class lexical [[Closure (computer science)|closures]], [[Function object#Other meanings|functors (parametric modules)]], [[exception handling]], [[effect system|effect handling]], and incremental generational [[garbage collection (computer science)|automatic garbage collection]].

OCaml is notable for extending ML-style type inference to an object system in a general-purpose language. This permits [[structural subtyping]], where object types are compatible if their method signatures are compatible, regardless of their declared [[Inheritance (object-oriented programming)|inheritance]] (an unusual feature in statically typed languages).

A [[foreign function interface]] for [[Linker (computing)|linking]] to [[C (programming language)|C]] primitives is provided, including language support for efficient numerical [[Array data structure|arrays]] in formats compatible with both C and [[Fortran]]. OCaml also supports creating libraries of OCaml functions that can be linked to a ''main'' program in C, so that an OCaml library can be distributed to C programmers who have no knowledge or installation of OCaml.

Although OCaml does not have a macro system as an indivisible part of the language ([[metaprogramming]]), i.e. built-in support for [[Preprocessor|preprocessing]], the [https://ocaml.org/docs/metaprogramming OCaml platform does officially support a library for writing such preprocessors]. These can be of two types: one that works at the source code level (as in C), and one that works on the [[Abstract syntax tree|Abstract Syntax Tree]] level. The latter, which is called PPX, acronym for Pre-Processor eXtension, is the recommended one.

The OCaml distribution contains:
* [[Lexical analysis]] and [[parsing]] tools called ''ocamllex'' and ''ocamlyacc''
* [[Debugger]] that supports stepping backwards to investigate errors
* [[Documentation generator]]
* [[Profiler (computer science)|Profiler]] – to measure performance
* Many general-purpose [[Library (computing)|libraries]]

The native code compiler is available for many platforms, including [[Unix]], [[Microsoft Windows]], and [[Apple Inc.|Apple]] [[macOS]]. Portability is achieved through native [[code generation (compiler)|code generation]] support for major architectures: 

* [[X86-64]] (AMD64), [[RISC-V]], and [[ARM64]] (in OCaml 5.0.0 and higher)<ref>{{cite web|url=https://github.com/ocaml/ocaml/tree/trunk/asmcomp|title=ocaml/asmcomp at trunk · ocaml/ocaml · GitHub|work=GitHub|access-date=2 May 2015}}</ref>
* [[IBM Z]] (before OCaml 5.0.0, and back in OCaml 5.1.0)
* [[Power ISA|Power]] (before OCaml 5.0.0, and due to reappear in OCaml 5.2.0)
* [[IA-32]] and [[ARM architecture|ARM]] (before OCaml 5.0.0)
* [[SPARC]] (before OCaml 4.06.0)
* [[DEC Alpha]], [[HPPA]], [[IA64]] and [[MIPS architecture|MIPS]] (before OCaml 4.00.0)

The [[bytecode]] [[compiler]] supports operation on any 32- or 64-bit architecture when native code generation is not available, requiring only a C compiler.

OCaml bytecode and native code programs can be written in a [[Thread (computer science)|multithreaded]] style, with [[Preemption (computing)|preemptive]] context switching. OCaml [[Thread (computing)|threads]] in the same domain<ref>A domain is a unit of parallelism in OCaml, a domain usually corresponds to a CPU core</ref> execute by [[Time-sharing|time sharing]] only. However, an OCaml program can contain several domains.