On Sun, 10 Jul 2011, Felipe Almeida Lessa wrote:
On Sat, Jul 9, 2011 at 7:58 AM, Henning Thielemann
<lemm...@henning-thielemann.de> wrote:
My stream processors are not Arrows, because 'first' cannot be implemented.
However, 'arr' and '.' can be implemented.
...
Since I have no Arrow instance I even have to write my own combinators that
are counterparts to (&&&) and friends.
If you have arr, (.) and (&&&), then you have first as well:
f **** g = (arr fst >>> f) &&& (arr snd >>> g)
first' f = f **** arr id
Am I missing something here? =)
I have only something like (&&&), but not precisely (&&&).
I have for instance
parallel :: (Monoid b) => T a b -> T a b -> T a b
The arrow (T a b) emits a value of type 'b' for every incoming event of
type 'a', but may also emit a 'b' without any input trigger.
Monoid.mappend is used to merge the events if both input arrows generate
an output at the same time.
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