Home > Articles > Programming

This chapter is from the book

1.5 What We Can Learn From ...

Luckily, a large amount of existing knowledge is helpful in the creation of software languages. In this book, I draw mainly from three sources: natural-language studies, traditional computer language theories, and graph grammars. And although this field does not have a great influence in this book, I also include a short description of the work from the visual languages community, because it is rather similar to traditional computer language theories but aimed at graphical, or visual, languages.

1.5.1 Natural-Language Studies

When someone who is not a computer scientist hears the word language, the first thing that comes to mind is a natural language, such as the person's mother tongue. Although software languages are artificially created and natural languages are not, we can still learn a lot from the studies of natural languages. (See Background on Natural-Language Studies.) Of course, we cannot use every part of it. For example, software languages do not have a sound structure, so there is no need to study phonology.1 However, all other fields of study are as relevant to software languages as they are to natural languages. It must be noted that these fields of study are, of course, interrelated. One cannot reasonably study one aspect of a language, such as morphology, without being at least aware of the other aspects, such as syntaxis.

It is interesting to see that with the advent of mobile phones, the phenomenon of multiple syntaxes is also emerging in natural language. A second morphological and syntactical structuring of natural language expressions has developed; for example, everybody understands the next two phrases as being the same: 4u and for you.

1.5.2 Traditional Language Theory

In the late 1950s, the fundamentals of current-day theory for textual software languages were laid down by such people as Chomsky [1965] and Greibach [1965, 1969]. In the 1970s and 1980s, these fundamentals were used by, among others, Aho and Ullman to develop the theory of compiler construction [Hopcroft and Ullman 1979, Aho et al. 1985]. In this research, grammars were used to specify textual languages.

The original motivation for the study of grammars was the description of natural languages. While linguists were studying certain types of grammars, computer scientists began to describe programming languages by using a special notation for grammars: Backus-Naur Form (BNF). This field has brought us a lot of knowledge about compiler technology. For more information, see Background on Grammars (p. 48), Background on Compiler Technology (p. 96), and Background on Backus-Naur Format (p. 116).

1.5.3 Graph Theory

Graphs have long been known as mathematical constructs consisting of objects—called nodes or vertices—and links—called edges or arcs—between them. Over the ages, mathematicians have built up a large body of theory about graphs: for instance, algorithms to traverse all nodes, connectivity theorems, isomorphisms between two graphs. All this has been brought to use in graph grammars.

Graphs grammars specify languages, usually graphical (visual) languages, by a set of rules that describe how an existing graph can be changed and added to. Most graph grammars start with an empty graph, and the rules specify how the expressions in your language can be generated. For more information, see Background on Graphs and Trees (p. 50).

1.5.4 The Visual-Languages Community

Visual-language design is our last background area. Although it started later than textual languages, the advance of visual languages has also been investigated for a few decades now. This area can be roughly divided into two parts: one in which grammars are based on graphs and one that does not use graph grammars.

In this book, I do not use visual language, the term commonly used in this community. Instead, I use graphical language, a phrase I find more appropriate because textual languages are also visual, while at the same time most nontextual languages are denoted by some sort of nodes with edges or connectors between them: in other words, denoted like a graph.

Non-Graph-Grammar Based

The non-graph-grammar-based research is concerned mostly with scanning and parsing visual-language expressions: in other words, diagrams. Several formalisms for denoting the rules associated with scanning and parsing have been proposed: Relational Grammars [Weitzman and Wittenburg 1993], Constrained Set Grammars [Marriott 1995], and (Extended) Positional Grammars [Costagliola and Polese 2000]. For a more extensive overview, see Marriott and Meyer [1997] or Costagliola et al. [2004].

Virtually all work in this area focuses on the recognition of basic graphical symbols and grouping them into more meaningful elements, although some researchers stress the fact that more attention needs to be paid to language concepts, which in this field is often called semantics. Often, these semantics are added in the form of attributes to the graphical symbols. This is very different from the metamodeling point of view. For instance, although UML is a visual language, its metamodel does not contain the notions of box, line, and arrow.

Common to all formalisms is the use of an alphabet of graphical symbols. These graphical symbols hold information on how to materialize the symbol to our senses, such as rendering info, position, color, and border style. Next to the alphabet, various types of spatial relationships are commonly defined, based on position (left to, above), attaching points (end point of a line touches corner of rhombus), or attaching areas by using the coordinates of the symbol's bounding box or perimeter (surrounds, overlaps). Both the alphabet and the spatial relationships are used to state the grammar rules that define groupings of graphical symbols.

Although the work in this area does not use graph grammars, the notion of graphs is used. The spatial relationships can be represented in the form of a graph, a so-called spatial-relationship graph [Bardohl et al. 1999], in which the graphical symbols are the nodes, and an edge between two nodes represents a spatial relationship between the two symbols.

Graph-Grammar Based

The graph-grammar community has also paid attention to visual-language design, most likely because the graph formalism itself is a visual one. In this field, more attention is paid to language concepts. In fact, the graph-grammar handbook states that the graphical symbols needed to materialize the language concepts to the user are attached as attribute values to the graph nodes representing the language concepts, an approach that is certainly different from the non-graph-grammar-based field.

Another distinctive difference is that the non-graph-grammar-based approach uses grammar rules with only one nonterminal on the left-hand side: that is, grammar rules in a context-free format. Graph grammars, on the other hand, may contain rules that have a graph as the left-hand side: that is, grammar rules in a context-sensitive format.

A large number of tools are able to create development environments for visual languages. These include, among others, DiaGen [Minas and Viehstaedt 1995], GenGed [Bardohl 1999], AToM3 [de Lara and Vangheluwe 2002], and VL-Eli [Kastens and Schmidt 2002].

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020