Here are some examples of things you can do by reusing the lens machinery:
-- Insert a 1 after the 5th element
over (Pipes.Parse.splitAt 5) (<* yield 1)
-- Replace the first group of consecutive matching elements with 1
set (Pipes.Parse.group . Pipes.Extras.output) 1
-- Replace each line with "FOO"
over (Pipes.ByteString.lines . Pipes.Group.individually) (\p ->
yield "FOO" >> for p discard)
On 03/06/2016 08:31 AM, Thomas Wilkinson wrote:
Do you sometimes need to `set (span even)` or `set group`? When is
that helpful?
On Sunday, March 6, 2016 at 4:14:21 PM UTC, Gabriel Gonzalez wrote:
I would prefer to keep them the way they are, because the full
`Lens` functionality isn’t used just for `zoom` but also for other
utilities like `over` or `set`. It’s easier to just warn users
that a lens is improper than to create parallel versions of every
utility that a person might want to use with these `Lens`es.
On Mar 6, 2016, at 6:06 AM, Thomas Wilkinson
<[email protected] <javascript:>> wrote:
I am slightly freaked out by the `Lens`es provided by
`Pipes.Parse` being 'improper'. Could they not be `Getter`s
instead?
type Splitter a m = forall x. Getter (Producer a m x)
(Producer a m (Producer a m x))
-- Should have " join . view sp == id " for any sp ::
Splitter a m and p :: Producer a m r
span :: Monad m => (a -> Bool) -> Splitter a m
splitAt :: Monad m => Int -> Splitter a m
groupBy :: Monad m => (a -> a -> Bool) -> Splitter a m
group :: (Monad m, Eq a) => Splitter a m
-- would replace `zoom`
split :: Splitter a m -> Parser a m r -> Parser a m r
split sp st = StateT $ \p -> fmap (fmap join) (runStateT st
(p^.sp))
This means that users would sometimes have to use `zoom` and
sometimes have to use `split`, which might be annoying. But it
feels better than having fake `Lens`es somehow.
--
You received this message because you are subscribed to the
Google Groups "Haskell Pipes" group.
To unsubscribe from this group and stop receiving emails from it,
send an email to [email protected] <javascript:>.
To post to this group, send email to [email protected]
<javascript:>.
--
You received this message because you are subscribed to the Google
Groups "Haskell Pipes" group.
To unsubscribe from this group and stop receiving emails from it, send
an email to [email protected]
<mailto:[email protected]>.
To post to this group, send email to [email protected]
<mailto:[email protected]>.
--
You received this message because you are subscribed to the Google Groups "Haskell
Pipes" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
