Scheme todomvc

demo @ https://amirouche.github.io/scheme-todomvc/

Introduction

This repository host a version of todomvc that is powered by biwascheme interpreter, by snabbdom library and inspired from react / redux and elm architecture.

biwascheme is a scheme interpreter written in javascript that implements r7rs and r6rs. It both works in the browser and in nodejs.

snabbdom is functional virtual DOM library.

reactjs is javascript library which introduced the use of declarative views using virtual dom library which diff and patch the DOM efficently.

redux is “a predictable state container for JavaScript apps” otherwise said it handles what reactjs doesn't ie. it deals with the communication between view components and the backend. It also has the responsability to deal with the global state of the app.

How it works

The entry point is the app procedure which takes as arguments the following:

• container the dom node that will be used for rendering
• init a procedure that will return the initial state of the app
• view the procedure that takes state as argument and will render the application according to that state. It must return sxml-like datastructure with on-foo attribute to bind events to callbacks called actions.

actions

Actions are created from scheme procedure which have the following signature: state -> event -> state. Hence they return the new state of the application.

Here is an example action:

(define (title-clicked state)
  (lambda (event)
	(if (null? state) 
	    "How are you doing?"
		'())))

Actions are directly bound to events in the sxml. For instance:

(define (view state)
  `(h1 (@ (on-click . ,title-clicked))
       "Héllo World!"))

There is no reducers.

Read the source

All this is implemented in main.scm.

Where do we go from here?

Here are the things that can be done to improve further this prototype:

• Make use of ajax
• Build isomorphic app
• Make use of history api

Anything else?

Comments and feedback welcome.