Joel Reymont wrote:
> How does pattern matching work with HList?
> I would like to pass a HList to a function and only match if a
> certain field had a certain value.
The code below defines the function foo that accepts a record and
yields one value if the field PtX of the record has the value
On Thu, Jan 05, 2006 at 11:14:18PM -0800, [EMAIL PROTECTED] wrote:
> David Roundy wrote:
> > The only solution I can imagine would be to implement a class for each
> > field name. i.e. the only reasonble type of f I can imagine is
> > something like
> >
> > f :: Integral i, RecordHasField_foo i r
How does pattern matching work with HList?
I would like to pass a HList to a function and only match if a
certain field had a certain value.
On Jan 6, 2006, at 7:14 AM, [EMAIL PROTECTED] wrote:
*Test> :t accessor
accessor :: (HasField l r v) => r -> l -> v
--
http://wager
David Roundy wrote:
> The only solution I can imagine
> would be to implement a class for each field name. i.e. the only reasonble
> type of f I can imagine is something like
>
> f :: Integral i, RecordHasField_foo i r => r -> r
>
> But that's a very complicated solution, and once one implemented
> This change "solves" the problem that different records in a single
> namespace cannot share field names in a simple manner.
As mentioned elsewhere, you'd also need to remove the functional update
feature to fix this namespace problem.
> In order to allow the writing of records code with is bot
On Wed, Jan 04, 2006 at 03:03:40PM -0800, John Meacham wrote:
> On Wed, Jan 04, 2006 at 08:55:39AM -0500, David Roundy wrote:
> > Ah, good point, I hadn't thought about that. My proposal was to keep
> > record updates which would indeed mean that we'd need to require that all
> > "foo"s in a given
On Wed, Jan 04, 2006 at 08:55:39AM -0500, David Roundy wrote:
> Ah, good point, I hadn't thought about that. My proposal was to keep
> record updates which would indeed mean that we'd need to require that all
> "foo"s in a given data type have the same type. Which I don't think is a
> bad thing e
Hello,
On 1/4/06, David Roundy <[EMAIL PROTECTED]> wrote:
> > What happens to record updates?
> >
> > setFoo x r = r { foo = x }
> >
> > Or is the proposal to remove updates as well?
>
> Ah, good point, I hadn't thought about that. My proposal was to keep
> record updates which would indeed mean
On 2006-01-04, David Roundy <[EMAIL PROTECTED]> wrote:
> On Wed, Jan 04, 2006 at 02:17:27PM +, John Goerzen wrote:
> Haskell 98 already requires you to code up set* functions (provided you
> want them), so I'd only be doubling the amount of work you need to do. If
> you can get by with the exi
On Wed, Jan 04, 2006 at 02:17:27PM +, John Goerzen wrote:
> On 2006-01-02, David Roundy <[EMAIL PROTECTED]> wrote:
> > My proposal is simply to remove the automatic declaration of accessor
> > functions. In Haskell 98,
> >
> > data FooBar = Foo { foo :: Int } | FooBar = { foo :: Int, bar :: In
On 2006-01-02, David Roundy <[EMAIL PROTECTED]> wrote:
> My proposal is simply to remove the automatic declaration of accessor
> functions. In Haskell 98,
>
> data FooBar = Foo { foo :: Int } | FooBar = { foo :: Int, bar :: Int }
I would find this to be incredibly annoying. The fact that these
a
On Wed, Jan 04, 2006 at 11:53:59AM +0100, Ulf Norell wrote:
>
> On Jan 4, 2006, at 2:25 AM, Dylan Thurston wrote:
>
> >On Tue, Jan 03, 2006 at 02:41:40PM -0800, Ashley Yakeley wrote:
> >>David Roundy wrote:
> >>>On Mon, Jan 02, 2006 at 04:23:32PM -0800, Ashley Yakeley wrote:
> >One open quest
On Jan 4, 2006, at 2:25 AM, Dylan Thurston wrote:
On Tue, Jan 03, 2006 at 02:41:40PM -0800, Ashley Yakeley wrote:
David Roundy wrote:
On Mon, Jan 02, 2006 at 04:23:32PM -0800, Ashley Yakeley wrote:
One open question (in my mind) would be whether we'd allow
data Foo = FooInt { foo :: Int } |
On Tue, Jan 03, 2006 at 02:41:40PM -0800, Ashley Yakeley wrote:
> David Roundy wrote:
> >On Mon, Jan 02, 2006 at 04:23:32PM -0800, Ashley Yakeley wrote:
> >>>One open question (in my mind) would be whether we'd allow
> >>>
> >>>data Foo = FooInt { foo :: Int } | FooChar { foo :: Char }
> >>>
> >>>I
David Roundy wrote:
On Mon, Jan 02, 2006 at 04:23:32PM -0800, Ashley Yakeley wrote:
One open question (in my mind) would be whether we'd allow
data Foo = FooInt { foo :: Int } | FooChar { foo :: Char }
In the "new" system, there's no reason this need be illegal.
How would this behave?
dat
On Mon, Jan 02, 2006 at 04:23:32PM -0800, Ashley Yakeley wrote:
> > One open question (in my mind) would be whether we'd allow
> >
> > data Foo = FooInt { foo :: Int } | FooChar { foo :: Char }
> >
> > In the "new" system, there's no reason this need be illegal.
>
> How would this behave?
>
>
In article <[EMAIL PROTECTED]>,
David Roundy <[EMAIL PROTECTED]> wrote:
> One open question (in my mind) would be whether we'd allow
>
> data Foo = FooInt { foo :: Int } | FooChar { foo :: Char }
>
> In the "new" system, there's no reason this need be illegal.
How would this behave?
data Fo
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