Martin Sulzmann, Jeremy
Waznyhttp://www.informatik.uni-trier.de/%7Eley/db/indices/a-tree/w/Wazny:Jeremy.html,
Peter J.
Stuckeyhttp://www.informatik.uni-trier.de/%7Eley/db/indices/a-tree/s/Stuckey:Peter_J=.html:
A Framework for Extended Algebraic Data Types. FLOPS
On Sat, Jul 3, 2010 at 4:28 PM, Dan Doel dan.d...@gmail.com wrote:
It's potentially not just a violation of intent, but of soundness. The
following code doesn't actually work, but one could imagine it working:
class C a b | a - b
instance C () a
-- Theoretically works because C a b, C a
On Wed, 23 Jun 2010 00:14:03 -0700, Simon Peyton-Jones simo...@microsoft.com
wrote:
I'm interested in situations where you think fundeps work and type families
don't. Reason: no one knows how to make fundeps work cleanly with local type
constraints (such as GADTs).
Simon,
I have run into
On Sat, Jul 3, 2010 at 3:32 AM, Kevin Quick qu...@sparq.org wrote:
On Wed, 23 Jun 2010 00:14:03 -0700, Simon Peyton-Jones
simo...@microsoft.com wrote:
I'm interested in situations where you think fundeps work and type
families don't. Reason: no one knows how to make fundeps work cleanly with
On Saturday 03 July 2010 2:11:37 pm David Menendez wrote:
{-# LANGUAGE MultiParamTypeClasses #-}
{-# LANGUAGE FunctionalDependencies #-}
{-# LANGUAGE FlexibleInstances, UndecidableInstances #-}
class C a b c | a - b, a - c where
op :: a - b - c
instance C Bool a a where op _ =
On Sat, 03 Jul 2010 12:48:56 -0700, Dan Doel dan.d...@gmail.com wrote:
Then the instance declares infinitely many instances C Bool a a. This is a
violation of the fundep. Based on your error message, it looks like it ends up
treating the instance as the first concrete 'a' it comes across, but
On Saturday 03 July 2010 4:01:12 pm Kevin Quick wrote:
As a side note, although I agree it abuses the fundeps intent, it was handy
for the specific purpose I was implementing to have a no-op/passthrough
instance of op. In general I like the typedef approach better, but it
looks like I must
On Sat, 03 Jul 2010 13:28:44 -0700, Dan Doel dan.d...@gmail.com wrote:
As a side note, although I agree it abuses the fundeps intent, it was handy
for the specific purpose I was implementing to have a no-op/passthrough
instance of op. In general I like the typedef approach better, but it
| Here's a concrete case I recently ran into:
|
| type family SomeOtherTypeFamily a
| class SomeClass a where type SomeType a
| instance a ~ SomeOtherTypeFamily b = SomeClass a where
|type SomeType a = (b,Int)
|-- (error) Not in scope: type variable `b'
|
| The same thing
Claus
| I'm interested in situations where you think fundeps work
| and type families don't. Reason: no one knows how to make
| fundeps work cleanly with local type constraints (such as GADTs).
|
| If you think you have such as case, do send me a test case.
|
| Do you have a wiki
| Well, from looking at the documentation, it looks like I could maybe
| use a type family if I could write:
|
| class (DerivedOf a ~ derived) = Typecheck a derived where
| ...
That's the right idiom yes. But see my message of a few minutes ago... It's
neater still to remove the
On Thu, Jul 1, 2010 at 7:54 PM, Simon Peyton-Jones simo...@microsoft.comwrote:
| Also, what is the difference between fundeps and type families
| wrt local type constraints? I had always assumed them to be
| equivalent, if fully implemented. Similar to logic vs functional
| programming,
Simon Peyton-Jones wrote:
I'm interested in situations where you think fundeps work and type
families don't. Reason: no one knows how to make fundeps work cleanly
with local type constraints (such as GADTs).
If you think you have such as case, do send me a test case.
As an example, is
I think your problem here is that there's no mention of `a' on the
left-hand size of from_val's type signature; you either need to use
MPTC+fundep to associate what result is compared to a, or else use a
phantom type parameter of Val to make it data Val result a = ... and
then from_val :: Val
| I think your problem here is that there's no mention of `a' on the
| left-hand size of from_val's type signature; you either need to use
| MPTC+fundep to associate what result is compared to a, or else use a
| phantom type parameter of Val to make it data Val result a = ... and
| then
I'm interested in situations where you think fundeps work and type families
don't. Reason: no one knows how to make fundeps work cleanly with local type
constraints (such as GADTs).
If you think you have such as case, do send me a test case.
Well, from looking at the documentation, it
I'm interested in situations where you think fundeps work
and type families don't. Reason: no one knows how to make
fundeps work cleanly with local type constraints (such as GADTs).
If you think you have such as case, do send me a test case.
Do you have a wiki page somewhere collecting
On 23 June 2010 13:46, Evan Laforge qdun...@gmail.com wrote:
I have a parameterized data type:
data Val result = VNum Double | VThunk (SomeMonad result)
type Environ result = Map Symbol (Val result)
I have a class to make it easier to typecheck Vals:
class Typecheck a where
from_val ::
On Wednesday 23 June 2010 05:46:46, Evan Laforge wrote:
I have a parameterized data type:
data Val result = VNum Double | VThunk (SomeMonad result)
type Environ result = Map Symbol (Val result)
I have a class to make it easier to typecheck Vals:
class Typecheck a where
from_val :: Val
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