iteratee Couple functions for combining Enueratees with Enumerators and Iteratees

[John Lato]

Iteratee-0.8.7.3 is on hackage with these functions, and 'ifold' as well.

Thanks for the info about the list; I'll look into it.

John

On Fri, Nov 25, 2011 at 12:15 PM, Michael Baikov <manpacket at gmail.com> wrote:
> I never used enumerator package actually so I don't know :) Just make
> sure that you add proper version of ($=), the one with forall.
>
> Btw, there is something wrong with maillist. I don't see this
> conversation in maillist archives on the website for example.
>
> On Fri, Nov 25, 2011 at 7:02 PM, John Lato <jwlato at gmail.com> wrote:
>> I've been meaning to add these for a while actually; I should be able
>> to upload a new version after work today.
>>
>> Would you have any objection to using the same fixities as in the
>> enumerator package?
>>
>> John L.
>>
>> On Fri, Nov 25, 2011 at 6:55 AM, Michael Baikov <manpacket at gmail.com> wrote:
>>> One more version, clean on typelevel and without unsafeCoerce
>>>
>>>
>>> ($=) :: (Nullable s1, Nullable s2, Monad m) => (forall a. Enumerator
>>> s1 m a) -> Enumeratee s1 s2 m b -> Enumerator s2 m b
>>> ($=) enum enee iter = enum (enee iter) >>= run
>>>
>>>
>>> On Fri, Nov 25, 2011 at 2:14 PM, Michael Baikov <manpacket at gmail.com> wrote:
>>>> Currently we have two nice functions for combining Enumeratees ><> and
>>>> <>< which can be used to produce chains of Enumeratees. I think that
>>>> it will be nice to have those functions as well:
>>>>
>>>>
>>>> -- this implementation relies on unsafeCoerce to keep type signature
>>>> nice and clean
>>>> -- so it is requred to import Unsafe.Coerce
>>>>
>>>> --| Combines Enumerator which produces stream of s and Enumeratee
>>>> which transforms stream of s to stream
>>>> -- of s' to into Enumerator which produces stream of s'
>>>> ($=) :: (Nullable s, Nullable s', Monad m) => Enumerator s m a ->
>>>> Enumeratee s s' m b -> Enumerator s' m b
>>>> ($=) enum enee iter = (unsafeCoerce enum) (enee iter) >>= run
>>>>
>>>>
>>>>
>>>> -- this implementation leaves type signature a bit messy, but without
>>>> using unsafeCoerce
>>>>
>>>> --| Combines Enumerator which produces stream of s and Enumeratee
>>>> which transforms stream of s to stream
>>>> -- of s' to into Enumerator which produces stream of s'
>>>> ($=) :: (Nullable s, Nullable s', Monad m) => Enumerator s m (Iteratee
>>>> s' m a) -> Enumeratee s s' m a -> Enumerator s' m a
>>>> ($=) enum enee iter = enum (enee iter) >>= run
>>>>
>>>>
>>>> --| Combines Enumeratee from s to s' and Iteratee which consumes s' to
>>>> into Iteratee which consumes s
>>>> (=$) :: (Nullable s, Nullable s', Monad m) => Enumeratee s s' m a ->
>>>> Iteratee s' m a -> Iteratee s m a
>>>> (=$) = (.) joinI
>>>>
>>>>
>>>> (=$) is mostly to keep sources clean, but ($=) can be used to
>>>> enumerate any given Iteratee over list of several different data
>>>> sources
>>>> (but type of the source can be transformed to type of Iteratee using
>>>> Enumeratee) just by transforming them to a single type and performing
>>>> foldM.
>>>>
>>>
>>
>