I'm wondering if anyone's run into this problem before, and if there's a
common solution.
In Yesod, we have applicative forms (based originally on formlets). These
forms are instances of Applicative, but not of Monad. Let's consider a
situation where we want to get some user input to fill out a
It's not a solution per se, but it seems to me that there's no need for the
Monad superclass constraint on MonadIO. If that were removed, we could
just have
class LiftIO t where
liftIO :: IO a - t a
and it would Just Work.
On Tue, Oct 1, 2013 at 1:58 AM, Michael Snoyman
Maybe this is needed new typeclass ApplicativeTrans?
2013/10/1 Michael Snoyman mich...@snoyman.com
I'm wondering if anyone's run into this problem before, and if there's a
common solution.
In Yesod, we have applicative forms (based originally on formlets). These
forms are instances of
What about (Compose Form IO) Blog type? Form is Applicative, IO — the same,
their composition should be Applicative as well (one good thing about
Applicatives — they really compose). Take a look at Control.Compose module.
Отправлено с iPad
01 окт. 2013 г., в 10:58, Michael Snoyman
On Tue, 1 Oct 2013 02:21:13 -0500, John Lato jwl...@gmail.com wrote:
It's not a solution per se, but it seems to me that there's no need for the
Monad superclass constraint on MonadIO. If that were removed, we could
just have
class LiftIO t where
liftIO :: IO a - t a
and it would
On Tue, Oct 01, 2013 at 09:29:00AM +0200, Niklas Haas wrote:
On Tue, 1 Oct 2013 02:21:13 -0500, John Lato jwl...@gmail.com wrote:
It's not a solution per se, but it seems to me that there's no need for the
Monad superclass constraint on MonadIO. If that were removed, we could
just have
On 10/01/2013 07:58 AM, Michael Snoyman wrote:
I'm wondering if anyone's run into this problem before, and if there's a
common solution.
In Yesod, we have applicative forms (based originally on formlets).
These forms are instances of Applicative, but not of Monad. Let's
consider a situation
On Tue, Oct 01, 2013 at 09:29:00AM +0200, Niklas Haas wrote:
On Tue, 1 Oct 2013 02:21:13 -0500, John Lato jwl...@gmail.com wrote:
It's not a solution per se, but it seems to me that there's no need for the
Monad superclass constraint on MonadIO. If that were removed, we could
just have
* Tom Ellis tom-lists-haskell-cafe-2...@jaguarpaw.co.uk [2013-10-01
09:20:23+0100]
On Tue, Oct 01, 2013 at 09:29:00AM +0200, Niklas Haas wrote:
On Tue, 1 Oct 2013 02:21:13 -0500, John Lato jwl...@gmail.com wrote:
It's not a solution per se, but it seems to me that there's no need for
From what you've said, it sounds like you can already write:
serverSide :: IO a - Form a
This seems elegant enough to me for your needs. Just encourage it as an
idiom specific to Forms.
myBlogForm = Blog $ titleForm * serverSide getCurrentTime *
contentsForm
Could you abstract
On Tue, Oct 01, 2013 at 12:11:23PM +0300, Roman Cheplyaka wrote:
Shouldn't it be an *Applicative* constraint?
class Applicative t = ApplicativeIO t where
liftIO :: IO a - t a
and require that
liftIO (pure x) = pure x
liftIO (f * x) = liftIO f * liftIO x
There is now a big white stripe in the Haskell.org's header (see the
screenshot).
Roman
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Tom Ellis wrote:
Shouldn't it be an *Applicative* constraint?
class Applicative t = ApplicativeIO t where
liftIO :: IO a - t a
and require that
liftIO (pure x) = pure x
liftIO (f * x) = liftIO f * liftIO x
Seems like ApplicativeIO makes more sense than MonadIO, which
Dan Burton wrote:
From what you've said, it sounds like you can already write:
serverSide :: IO a - Form a
This seems elegant enough to me for your needs. Just encourage it as an
idiom specific to Forms.
myBlogForm = Blog $ titleForm * serverSide getCurrentTime *
contentsForm
On Tue, Oct 01, 2013 at 03:17:40PM +0300, Yitzchak Gale wrote:
Tom Ellis wrote:
Shouldn't it be an *Applicative* constraint?
class Applicative t = ApplicativeIO t where
liftIO :: IO a - t a
and require that
liftIO (pure x) = pure x
liftIO (f * x) = liftIO f *
Hello everyone,
I’m excited to announce a brand new major version of fclabels. This library
provides first class labels that can act as bidirectional record fields.
The labels are implemented as lenses.
This new version contains some interesting new features like support for
polymorphic updates
Threepenny is now ready for public consumption, FIW.
On 23 May 2013 08:34, Vlatko Basic vlatko.ba...@gmail.com wrote:
Hi Heinrich,
Looks simple and interesting. I browsed the git, but not much docs yet.
Just examples, or have I looked at wrong places?
I see that API is still under heavy
The offending HTML is on line 93:
pbr//p
When I delete this paragraph element from the DOM, the ugly white bar goes
away.
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Apparently that element is generated by the wiki software, since most pages
want the view source / history buttons above the rest of the content.
jQuery('#mw-content-text p:first').hide()
-- Dan Burton
On Tue, Oct 1, 2013 at 8:17 AM, Dan Burton danburton.em...@gmail.comwrote:
The offending
On Tue, Oct 1, 2013 at 12:15 PM, Dan Burton danburton.em...@gmail.comwrote:
From what you've said, it sounds like you can already write:
serverSide :: IO a - Form a
This seems elegant enough to me for your needs. Just encourage it as an
idiom specific to Forms.
myBlogForm = Blog $
On Tue, Oct 1, 2013 at 10:24 AM, Alexey Uimanov s9gf4...@gmail.com wrote:
Maybe this is needed new typeclass ApplicativeTrans?
There's actually no problem with defining a MonadTrans instance for
non-monads. Obviously this can't follow the laws directly (since they're
defined in terms of
In MFow there is a Monad instance for formlets that make a lot of sense.
Apart from using liftIO inside an applicative formlets
it can do it that way also:
myBlogForm = do
t - liftIO getTime
Blog $ titleForm * return t * contentsForm
Which may look contrived, but instead of using
On Mon, Sep 30, 2013 at 11:58 PM, Michael Snoyman mich...@snoyman.comwrote:
I'm wondering if anyone's run into this problem before, and if there's a
common solution.
I ran into it, asked about it on SO, and followed your advice. :)
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Hi everyone,
I put together a Haskell logo decal designed to fit over the Apple logo on
a MacBook, and had a few made by macdecals.com. They came out great!
They're available here: http://www.macdecals.com/macbook-haskell . My
share of the proceeds will go to haskell.org, and macdecals.com has
Yitzchak Gale g...@sefer.org writes:
In fact, it even makes sense to define it as FunctorIO, with the only laws
being that liftIO commutes with fmap and preserves id, i.e., that it is a
natural transformation. (Those laws are also needed for ApplicativeIO and
MonadIO.)
Given that we are
Interesting. It's similar in spirit to basically a safe Coerce typeclass,
but for * - * types.
class Coerce a b where
coerce :: a - b
class Coerce1 f g where
coerce1 :: f a - g a
-- Dan Burton
On Tue, Oct 1, 2013 at 11:00 AM, John Wiegley jo...@fpcomplete.com wrote:
Hello all,
Normally, we don't worry *too* much about incorrect instances of standard
classes (Num, Eq, Ord) etc. They make the user's program wrong, but they
don't compromise the type system.
Unfortunately, with the LVish parallel programming library we do have a
situation where incorrect
Here are some examples:
-
data Foo = Bar | Baz
instance Eq Foo where
_ == _ = True
instance Ord Foo where
compare Bar Bar = EQ
compare Bar Baz = LT
compare _ _ = error I'm partial!
-
These would
I ordered mine!
Does anyone know if there is any place where I could order pre-made Haskell
t-shirt that benefits haskell.org too?
--
Kyle
On Tue, Oct 1, 2013 at 10:23 AM, Ryan Trinkle ryan.trin...@gmail.comwrote:
Hi everyone,
I put together a Haskell logo decal designed to fit over the
Bought the white one.
On Tue, Oct 1, 2013 at 5:50 PM, Kyle Hanson hanoo...@gmail.com wrote:
I ordered mine!
Does anyone know if there is any place where I could order pre-made
Haskell t-shirt that benefits haskell.org too?
--
Kyle
On Tue, Oct 1, 2013 at 10:23 AM, Ryan Trinkle
On Tue, Oct 1, 2013 at 3:50 PM, Kyle Hanson hanoo...@gmail.com wrote:
I ordered mine!
Does anyone know if there is any place where I could order pre-made
Haskell t-shirt that benefits haskell.org too?
I don't know where, but I just wanted to say thank you to both you and Ryan
and everyone
Hi all,
I'm pleased to announce the release of our new parallel-programming
library, LVish:
hackage.haskell.org/package/lvish
It provides a Par monad similar to the monad-par package, but generalizes
the model to include data-structures other than single-assignment variables
(IVars). For
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