## 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.