step

An experimental library for update functions

Step s msg o is inteneded to be the return value of an update function. It encodes a bunch of common update function patterns, uniting them under a simple mental model, that aims to both clean up code and make gluing isolated update functions together easier.

A mental model for update functions

A Step s msg o describes one step of an interaction. Here's a few things about the interactions we're talking about her

• Interactions can involve the end user of your app, external servers, javascript: anything you might need to coordinate with in an Elm app
• Interactions can be in one of a finite set of states. The states are represented by the type s
• Interactions change state in response to messages, actions from the outside world. The messages are represented by the type msg
• When responding to a message, the state of the interaction might change, and Cmds may be fired, potentially producing more messages.
• Interactions might go on indefinitely, or end. If they end, they result in a final value of type o. This might seem a little weird, but it has some nice properties

Install

elm package install xilnocas/step