pre-srfi / webui

scheme framework for the web browser

Home Page:https://pre-srfi.github.io/webui/demos/03-todomvc/

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Title

webui

Author

Amirouche BOUBEKKI

Status

Early Draft

Abstract

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.

Issues

??? Optional section that may point out things to be resolved. This will not appear in the final SRFI.

Rationale

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.

Specification

(webui-app patch! init view) → procedure

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 like on-click in the above example. PATCH! is described in the next section.

  • INIT is a thunk that returns the initial model for the application. It should return an immutable object.

  • VIEW is 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*

(webui-patch! node sxml)

(webui-style alist)

(webui-route pattern init view)

VIEW should be side-effect free, otherwise the behavior is not specified.

(webui-router routes)

(webui-change-route path)

(webui-xhr method headers path body)

(webui-app* patch! router xhr)

Implementation

??? 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.

Acknowledgements

Give credits where credits is due.

Copyright

Copyright (C) Amirouche BOUBEKKI (2020).

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

About

scheme framework for the web browser

https://pre-srfi.github.io/webui/demos/03-todomvc/


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