webui
Amirouche BOUBEKKI
Early Draft
This library describes a framework to build graphical user interface
based on sxml. It takes inspiration from
elm and Redux.
Unlike elm it is not strictly functional. It takes advantage of
diff + patch algorithm that powers virtual dom libraries such as
React, Preact and
snabbdom.
??? Optional section that may point out things to be resolved. This will not appear in the final SRFI.
The main advantage of the "virtual DOM" approach to build a graphical user interface is that the developer does not need to figure how to mutate the scene graph, or hierarchy of widgets, or as it is the case in the browser, the DOM nodes that must be added, updated or deleted.
The developer can focus on what application they want to build instead of how to build the application.
The diff + patch algorithm factors all the mutation operations inside this library making it possible to reduce non-functional code in the application, hence it is easier to think about the application.
The approach taken in elm that is strictly functional, and that rely on continuations (or if you prefer: callbacks) is verbose, and as matter of fact leads to code that is more difficult to reason about.
This library bridge the gap with the excellent testability of elm approach by passing procedures that have side-effects as arguments, that way it is trivial to mock behaviors that have side-effects during testing.
The fact that this library re-use the vocabulary of the most known graphical user interface pattern ie. Model-View-Controler is not a mistake.
webui-app takes the procedures PATCH!, INIT and VIEW and
return a procedure called "change" procedure.
Here is a minimal example use that describe the implementation of a game where you need to click on a button to increment a counter:
(define (on-click model event)
(+ model 1))
(define (view model)
`(div
(h1 "counter is " model)
(button (@ (on-click ,on-click)) "increment")))
(define change (webui-app webui-patch! (lambda () 0) view))-
PATCH!is a procedure that binds reactjs with scheme. It takes a description of the DOM using sxml that the user wants to display along with the controller procedures likeon-clickin the above example.PATCH!is described in the next section. -
INITis a thunk that returns the initial model for the application. It should return an immutable object. -
VIEWis a procedure that takes the model as argument and return the description of the expected DOM.
TODO: describe single direction data-flow.
TODO: describe the behavior of controllers.
webui-app is really useful to explain the gist of the approach or
prototyping. For real world web application that require calls to the
backend and url routes use webui-app*
VIEW should be side-effect free, otherwise the behavior is not
specified.
??? explanation of how it meets the sample implementation requirement (see process), and the code, if possible, or a link to it Source for the sample implementation.
Give credits where credits is due.
Copyright (C) Amirouche BOUBEKKI (2020).
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