Applicative bots

In Functional reactive partner dancing, I mentioned that (a) the partially applied leading and following types have boilerplate Applicative instances, and (b) the leading type corresponds to varying (reactive) values. Today I realized that those boilerplate instances are not very useful, and that they do not correspond to the Applicative instance of Reactive. In this post, I give a useful Applicative instance that does correspond to the Reactive instance. The instance definition is expressed in terms of the pair editor bot shown at the end of the “dancing” post, which seems to have a variety of applications.

The Applicative instance has one awkward aspect that suggests a tweak to the formulation of leading. I give simplified versions of pair editing and Applicative for the revised type. This change is in version 0.1 of the Bot libary.

Edit 2008-02-15: added FRP tags; prose tweak.

Continue reading ‘Applicative bots’ »

Functional reactive partner dancing

This note continues an exploration of arrow-friendly formulations of functional reactive programming. I refine the previous representations into an interactive dance with dynamically interchanging roles of follow and lead. These two roles correspond to the events and reactive values in the (non-arrow) library Reactive described in a few previous posts. The post ends with some examples.

The code described (with documentation and examples) here may be found in the new, experimental library Bot (which also covers mutant-bots and chatter-bots).

Continue reading ‘Functional reactive partner dancing’ »