Expressing data and instance declarations in the same syntax you express code and class definitions is an essential feature that enables "Instance First Development", and the "Instance Substitution Principal", as supported by OpenLaszlo, and described by Oliver Steele. And throwing declarative constraint based programming into that mix is really synergistically powerful and expressive.

https://news.ycombinator.com/item?id=21841054

DonHopkins on Dec 20, 2019 | root | parent | next [–]

My remark was just an old Java joke I repurposed for Ant!

"Java is a DSL for taking large XML files and converting them to stack traces." -Andrew Back

https://www.reddit.com/r/programming/comments/eaqgk/java_is_...

But in all seriousness:

OpenLaszlo used XML with embedded JavaScript in a way that let you extend XML by defining your own tags in XML+JavaScript. I've done a lot of work with it, and once you make your peace with XML (which seemed like a prudent thing to do at the time), it's a really productive enjoyable way to program! But that's more thanks to the design of OpenLaszlo itself, rather than XML.

https://en.wikipedia.org/wiki/OpenLaszlo

OpenLaszlo (which was released in 2001) inspired Adobe Flex (which was released in 2004), but Flex missed the point of several of the most important aspects of OpenLaszlo (first and foremost being cross platform and not locking you into Flash, which was the entire point of Flex, but also the declarative constraints and "Instance First Development" and the "Instance Substitution Principal", as defined by Oliver Steele).

https://en.wikipedia.org/wiki/Apache_Flex

https://blog.osteele.com/2004/03/classes-and-prototypes/

The mantle of constraint based programming (but not Instance First Development) has been recently taken up by the "Reactive Programming" craze (which is great, but would be better with a more homoiconic language that supported Instance First Development and the Instance Substitution Principle, which are different but complementary features with a lot of synergy). The term "Reactive Programming" describes a popular old idea: what spreadsheets had been doing for decades.

OpenLaszlo and Garnet (a research user interface system written by Brad Myers at CMU in Common Lisp) were exploring applying automatic constraints to user interface programming. Garnet started in the early 1990's. Before that, Ivan Sutherland's Sketchpad explored constraints in 1963, and inspired the Visual Geometry Project in the mid 1980's and The Geometer's Sketchpad in 1995.

https://en.wikipedia.org/wiki/Reactive_programming

http://www.cs.cmu.edu/afs/cs/project/garnet/www/garnet-home....

https://en.wikipedia.org/wiki/Sketchpad

https://web.archive.org/web/20160303205845/http://math.coe.u...

https://en.wikipedia.org/wiki/The_Geometer%27s_Sketchpad

I've written more about OpenLaszlo and Garnet:

What is OpenLaszlo, and what's it good for?

https://web.archive.org/web/20160312145555/http://donhopkins...

>Declarative Programming: Declarative programming is an elegant way of writing code that describes what to do, instead of how to do it. OpenLaszlo supports declarative programming in many ways: using XML to declare JavaScript classes, create object instances, configure them with automatic constraints, and bind them to XML datasets. Declarative programming dovetails and synergizes with other important OpenLaszlo techniques including objects, prototypes, events, constraints, data binding and instance first development.

Constraints and Prototypes in Garnet and Laszlo

https://web.archive.org/web/20160405015129/http://www.donhop...

>Garnet is an advanced user interface development environment written in Common Lisp, developed by Brad Meyers (the author of the article). I worked for Brad on the Garnet project at the CMU CS department back in 1992-3.

https://news.ycombinator.com/item?id=17360883

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