Editing Preprocessor (section)

===Specializing a language===
One of the unusual features of the [[Lisp programming language|Lisp]] family of languages is the possibility of using macros to create an internal DSL. Typically, in a large [[Lisp programming language|Lisp]]-based project, a module may be written in a variety of such [[minilanguage]]s, one perhaps using a [[SQL]]-based dialect of [[Lisp programming language|Lisp]], another written in a dialect specialized for [[Graphical user interface|GUI]]s or pretty-printing, etc. [[Common Lisp]]'s standard library contains an example of this level of syntactic abstraction in the form of the LOOP macro, which implements an Algol-like minilanguage to describe complex iteration, while still enabling the use of standard Lisp operators.

The [[MetaOCaml]] preprocessor/language provides similar features for external DSLs. This preprocessor takes the description of the semantics of a language (i.e. an interpreter) and, by combining compile-time interpretation and code generation, turns that definition into a compiler to the [[OCaml]] programming language—and from that language, either to bytecode or to native code.
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Please provide an authoritative cite defining "general purpose(sic) preprocessor" and
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==Preprocessors as template engines==
Any "general purpose preprocessor", like [[M4 (computer language)|M4]], can be used as a [[template processor|template engine]].

"General purpose preprocessors" and "general purpose template engines" are the same kind of softwares.
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