Editing Domain-specific language (section)

==Domain-specific language topics==
===External and Embedded Domain Specific Languages===
DSLs implemented via an independent interpreter or compiler are known as ''External Domain Specific Languages''. Well known examples include TeX or AWK. A separate category known as ''Embedded (or Internal) Domain Specific Languages'' are typically implemented within a host language as a library and tend to be limited to the syntax of the host language, though this depends on host language capabilities.<ref>{{cite web |last1=Fowler |first1=Martin |last2=Parsons |first2=Rebecca |title=Domain Specific Languages |url=https://martinfowler.com/books/dsl.html |access-date=6 July 2019}}</ref>

===Usage patterns===
There are several usage patterns for domain-specific languages:<ref name='Mernik05'>{{cite journal|first1=Marjan |last1=Mernik|first2=Jan |last2=Heering|first3=Anthony M. |last3=Sloane|title=When and how to develop domain-specific languages|journal=ACM Computing Surveys|volume=37|number=4|pages=316–344|year=2005|doi=10.1145/1118890.1118892}}</ref><ref name='Spinellis01'>{{cite journal|first1=Diomidis|last1=Spinellis|url=http://www.spinellis.gr/pubs/jrnl/2000-JSS-DSLPatterns/html/dslpat.html|title=Notable design patterns for domain specific languages|journal=Journal of Systems and Software|volume=56|number=1|pages=91–99|date=February 2001|doi=10.1016/S0164-1212(00)00089-3}}</ref>

* Processing with standalone tools, invoked via direct user operation, often on the command line or from a [[Makefile]] (e.g., grep for regular expression matching, sed, lex, yacc, the [[GraphViz]] toolset, etc.)
* Domain-specific languages which are implemented using programming language macro systems, and which are converted or expanded into a host general purpose language at compile-time or realtime
* As {{anchor|eDSL}}'''embedded domain-specific language''' ('''eDSL''')<ref>{{cite journal |last1=Felleisen |first1=Matthias |last2=Findler |first2=Robert Bruce |last3=Flatt |first3=Matthew |last4=Krishnamurthi |first4=Shriram |last5=Barzilay |first5=Eli |last6=McCarthy |first6=Jay |last7=Tobin-Hochstadt |first7=Sam |title=A Programmable Programming Language |journal=Communications of the ACM |date=March 2018 |volume=61 |issue=3 |pages=62–71 |doi=10.1145/3127323 |s2cid=3887010 |url=https://cacm.acm.org/magazines/2018/3/225475-a-programmable-programming-language/fulltext |access-date=15 May 2019|url-access=subscription }}</ref> also known as an '''internal domain-specific language''', is a DSL that is implemented as a library in a "host" programming language. The embedded domain-specific language leverages the syntax, semantics and runtime environment (sequencing, conditionals, iteration, functions, etc.) and adds domain-specific primitives that allow programmers to use the "host" programming language to create programs that generate code in the "target" programming language. Multiple eDSLs can easily be combined into a single program and the facilities of the host language can be used to extend an existing eDSL. Other possible advantages using an eDSL are improved [[type safety]] and better [[Integrated_development_environment|IDE]] tooling. eDSL examples: [[SQLAlchemy]] "Core" an SQL eDSL in [[Python (programming language)|Python]], [[Java Object Oriented Querying|jOOQ]] an SQL eDSL in [[Java (programming language)|Java]], [[LINQ]]'s "method syntax" an SQL eDSL in [[C Sharp (programming language)|C#]] and [https://github.com/Kotlin/kotlinx.html kotlinx.html] an [[HTML]] eDSL in [[Kotlin (programming language)|Kotlin]].
* Domain-specific languages which are called (at runtime) from programs written in general purpose languages like [[C (programming language)|C]] or [[Perl]], to perform a specific function, often returning the results of operation to the "host" programming language for further processing;  generally, an interpreter or [[virtual machine]] for the domain-specific language is embedded into the host application (e.g. [[format string]]s, a [[Regular expression|regular expression engine]])
* Domain-specific languages which are embedded into user applications (e.g., macro languages within spreadsheets)<ref name="stinson19910416">{{Cite magazine |last=Stinson |first=Craig |date=1991-04-16 |title=Building the Perfect Spreadsheet |url=https://books.google.com/books?id=_OEk1QOJYw0C&pg=PT112 |access-date=2025-03-14 |magazine=PC |pages=101–164}}</ref>  and which are (1) used to execute code that is written by users of the application, (2) dynamically generated by the application, or (3) both.

Many domain-specific languages can be used in more than one way.{{Citation needed|date=September 2009}} DSL code embedded in a host language may have special syntax support, such as regexes in sed, AWK, Perl or JavaScript, or may be passed as strings.

===Design goals===
Adopting a domain-specific language approach to software engineering involves both risks and opportunities. The well-designed domain-specific language manages to find the proper balance between these.

Domain-specific languages have important design goals that contrast with those of general-purpose languages:

* Domain-specific languages are less comprehensive.
* Domain-specific languages are much more expressive in their domain.
* Domain-specific languages should exhibit minimal [[Redundant code|redundancy]].

===Idioms===
In programming, [[Programming idiom|idioms]] are methods imposed by programmers to handle common development tasks, e.g.:

* Ensure data is saved before the window is closed.
* Edit code whenever command-line parameters change because they affect program behavior.

General purpose programming languages rarely support such idioms, but domain-specific languages can describe them, e.g.:

* A script can automatically save data.
* A domain-specific language can parameterize command line input.