Hello all,
not having a strong web development background, but rather coming from the
area of domain-specific languages, model-driven development, and IDE
development (i.e. building tools for developers and development platforms),
Elm made me curious because of a lot of the ideas and features that are
built into the language that I know from other technologies. While I
understand that Elm is specifically targeted to make the lives of front-end
web developers easier and offer them an alternative to JavaScript and the
zoo of libraries there, I'd like to discuss if Elm could become even bigger
eventually (especially given technologies like Electron that allow us
easily to target the desktop as well).
One of the key selling points for me is the thoroughness that is used to
identify what we know as the Elm Architecture. Elm guides you to define a
model of your "world" and to specify how this model changes ("update") due
to effects from outside or inside ("subscriptions" and "commands"). Also,
you define how the model is going to be presented to the user ("view"). And
Elm takes care of wiring these components together. It's great and I see
Elm as a great language not only for veterans, but also for beginners!
In model-driven development, there are a lot of similarities, but also some
differences. Often, your world is made up of several domains ("model
schemas"), and you define transformations from one domain to the other.
That means applications are composed of domains that are wired by
transformations. A system that allows you to build applications that work
that way is MPS, by Jetbrains <https://www.jetbrains.com/mps/>, in case you
would like to see an example.
One could say that we have a simplified version of that in the Elm
Architecture, where we define one domain ("model") and one transformation
("view") in which we transform our "domain model" to a "rendering model",
that is passed on to a rendering engine for display.
So, some of you might say "that's all nice and good, but why do you bring
it up"? Well, I really think that there is a lot of potential in the idea
of model-driven development and projectional editing and I feel like Elm
would be an interesting technology to build something like this on due to
its functional nature and thoroughness put into its architecture. I'd like
to discuss this with the community.
To make things a bit more specific, I wonder what you think about
generalizing the Elm Architecture in a way that we not only transform from
a domain model to a Html model (a.k.a. view), but to allow for a series of
transformations if necessary. I like that the current architecture allows
us to do something like that to a certain degree. Looking at the Mdl
package for example, I consider this a "Widget domain" and I can
incorporate it into my "view" function, basically reusing portions of their
"domain model to Html" transformation for my own purpuses.
But if I want to use Elm to transform gradually from a model of low
abstraction to Html via intermediate domains, it is hard to do. A
suggestion would be to have an optional callback called "transformations"
that takes in a model of type A and spits out a model of type B, which is
then again used as input for the final transformation step, which would
still be "view". Optional means that, if no transformation is defined, A ==
B.
I hope all of this does make a little bit of sense to some of you and I
really hope it is not too controversial.
Best,
Robert
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