akheron / lonna

A very popular library

Lonna

Experimental FRP library for Graphical User Interfaces. To be used in my Harmaja project.

Compared to Bacon.js

• Stateful Properties and EventStreams have an explicit scope which guarantees that they stay up-to-date for the required period. Scope can be global (active forever) or more limited, such as a GUI component lifetime. Access outside the explicit scope will cause thrown Errors.
• EventStreamSeed and PropertySeed abstractions for streams and properties that don't have a scope. These can be mapped, filtered etc, but need to be scoped before accessing the value. They are very lightweight which may prove to be a major performance improvement: when creating temporary streams in flatMap, for instance, there's no need to create a Dispatcher for everything.
• The scope decouples subscribers from EventStream/Property activation. This means that "cold observables" like Bacon.once cannot be EventStreams in Lonna. They will be EventStreamSeeds (what should I call it?) and can be used in constructs like flatMap as intermediary Observables.
• Because the scope guarantess freshness, the get() method in Property and Atom can be used for reliable synchronous access to current value. Also, a Property always has a value.
• More flexible Property interface that makes it easy to create properties that, for instance, extract their current value from the DOM or other external synchrnous source.
• Properties and Atoms always automatically skip duplicates, so no need for .skipDuplicates like in Bacon
• No Error events. I've found them quite counterproductive in my use cases.
• Simpler dispatch system, no Atomic Updates. However, when decomposition using map/combine is stateless which in itself guarantees that composed/decomposed state remains in sync
• Atoms included for read-write state, similarly Bus for read-write streams. Rudimentary lens system included for decomposing state.
• API consists of static methods instead of prototype methods. Is tree-shakable and easier to extend.