2009/6/10 Freddie Manners
<f.manners@gmail.com>
So, it may be that we've made Num a => Behavior a an instance of Num in which case this is valid code; I think the definition
a = liftA2 (+) b c
is more instructive. The point is that Behavior is an instance of Applicative, so we can apply a time-varying function (such as (+) b) to a time-varying argument (such as c) so that the answer is modified when either the function or the argument is.
Freddie
2009/6/10 Patai Gergely
<patai_gergely@fastmail.fm>
> Anyway, can you give any implementation of this example using the
> reactive library?
If b and c are signals (or behaviours as they are called in Reactive)
carrying Num values of the same type, you can simply say a = b + c, and
you're done. Signal a will be updated only when either b or c is
updated. Note that this must be understood in the context of laziness,
i.e. not a single sum is calculated until a sample of a is requested.
Gergely
--
http://www.fastmail.fm - One of many happy users:
http://www.fastmail.fm/docs/quotes.html
_______________________________________________
Reactive mailing list
Reactive@haskell.org
http://www.haskell.org/mailman/listinfo/reactive