Editing Reification (computer science) (section)

== Reflective programming languages ==
In the context of [[programming language]]s, reification is the process by which a user program or any aspect of a programming language that was implicit in the translated program and the run-time system, are  expressed in the language itself. This process makes it available to the program, which can inspect all these aspects as ordinary [[data]]. In [[Reflection (computer science)|reflective languages]], reification data is causally connected to the related reified aspect such that a modification to one of them affects the other. Therefore, the reification data is always a faithful representation of the related reified aspect {{clarification needed|date=April 2017}}. Reification data is often said to be made a [[first class object]]{{citation needed|date=April 2017}}. Reification, at least partially, has been experienced in many languages to date: in early [[Lisp (programming language)|Lisp dialects]] and in current [[Prolog| Prolog dialects]], programs have been treated as data, although the causal connection has often been left to the responsibility of the programmer. In [[Smalltalk]]-80, the compiler from the source text to bytecode has been part of the run-time system since the very first implementations of the language.<ref>J. Malenfant, M. Jacques and F.-N. Demers, [http://www2.parc.com/csl/groups/sda/projects/reflection96/docs/malenfant/ref96/ref96.html A Tutorial on Behavioral Reflection and its Implementation] {{webarchive|url=https://web.archive.org/web/20100528214857/http://www2.parc.com/csl/groups/sda/projects/reflection96/docs/malenfant/ref96/ref96.html |date=2010-05-28 }}</ref>

* The [[C (programming language)|C programming language]] reifies the low-level detail of [[memory address]]es.{{paragraph break}}Many programming language designs encapsulate the details of memory allocation in the compiler and the run-time system. In the design of the C programming language, the memory address is reified and is available for direct manipulation by other language constructs. For example, the following code may be used when implementing a memory-mapped device driver. The buffer pointer is a proxy for the memory address 0xB8000000.{{paragraph break}}<syntaxhighlight lang="c">
 char* buffer = (char*) 0xB8000000;
 buffer[0] = 10; 
</syntaxhighlight>
* [[Functional programming languages]] based on [[lambda-calculus]] reify the concept of a procedure abstraction and procedure application in the form of the [[Lambda calculus#Lambda calculus and programming languages|Lambda expression]].
* The [[Scheme (programming language)|Scheme]] programming language reifies [[continuations]] (approximately, the call stack).
* In [[C Sharp (programming language)|C#]], reification is used to make [[parametric polymorphism]] implemented in the form of generics as a first-class feature of the language.
* In the [[Java (programming language)|Java]] programming language, there exist "reifiable types" that are "completely available at run time" (i.e. their information is not erased during compilation).<ref>[http://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.7 The Java Language Specification, section 4.7], Java SE 7 Edition</ref>
* [[REBOL]] reifies code as data and vice versa.
* Many languages, such as [[Lisp (programming language)|Lisp]], [[JavaScript]], and [[Curl (programming language)|Curl]], provide an [[eval|<code>eval</code> or <code>evaluate</code> procedure]] that effectively reifies the language interpreter.
* The [[Logtalk]] framework for [[Prolog]] offers a means to explore reification in the context of [[logic programming]].
* [[Smalltalk]] and [[Actor model|Actor languages]] permit the reification of blocks and [[message passing|messages]],<ref>{{cite web|url=http://c2.com/cgi/wiki?SmalltalkBlocksAndClosures |title=Smalltalk Blocks And Closures |publisher=C2.com |date=2009-10-15 |accessdate=2010-10-09}}</ref> which are equivalent of lambda expressions in Lisp, and <code>thisContext</code> in Smalltalk, which is a reification of the current executing block.
* [[Homoiconicity|Homoiconic languages]] reify the syntax of the language as data that is understood by the language itself. This allows the user to write programs whose inputs and outputs are code (see [[Macro (computer science)|macros]], [[eval]]). Common representations of code include [[S-Expression|S-expressions]] (e.g. [[Clojure]], [[Lisp]]), and [[abstract syntax tree|abstract syntax trees]] (e.g [[Rust]]).