Re: [Haskell-cafe] Interfacing real-time stocks data API
I did not find such a library, but I am interested in Haskell trading automation too. BTW, I am developing package for testing trading systems, it can just download historical data from some free russian stock services for now. https://github.com/s9gf4ult/hadan If you interested we could join forces. 2013/10/9 Miro Karpis miroslav.kar...@gmail.com Please, did/does anybody tried to interface with Haskell some real-time stocks data API? If yes, please which one? So far I came down to ActveTick,... thanks, m. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Interfacing real-time stocks data API
Yes, the trading system, or code generator. It depends on what would be easier to implement. But firstly I need a simulator and history data crawler what I am working on. 2013/10/9 Miro Karpis miroslav.kar...@gmail.com Hi Alexey, thank you for response. You wrote that you are developing package for testing trading systems. Are you planning to also build a trading system? Regards, Miro On Wed, Oct 9, 2013 at 10:28 AM, Alexey Uimanov s9gf4...@gmail.comwrote: I did not find such a library, but I am interested in Haskell trading automation too. BTW, I am developing package for testing trading systems, it can just download historical data from some free russian stock services for now. https://github.com/s9gf4ult/hadan If you interested we could join forces. 2013/10/9 Miro Karpis miroslav.kar...@gmail.com Please, did/does anybody tried to interface with Haskell some real-time stocks data API? If yes, please which one? So far I came down to ActveTick,... thanks, m. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] FP relates events in NYC
Hi folks, I will be visiting New York at the end of the October and I would like to catch some cool Haskell events if possible. I'll be staying in the city from 29th of October to the 10th of November and I would like to plan my trip ahead. I am looking for anything nerdy: talks, seminars, user groups, etc Thanks - Dan ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Interfacing real-time stocks data API
I would love to see Haskell bindings for this: https://us.etrade.com/active-trading/api On Tue, Oct 8, 2013 at 1:26 PM, Miro Karpis miroslav.kar...@gmail.comwrote: Please, did/does anybody tried to interface with Haskell some real-time stocks data API? If yes, please which one? So far I came down to ActveTick,... thanks, m. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Interfacing real-time stocks data API
Yes, I also like that one. Problem is that they give access only to US citizens and some limited countries. m. -Original Message- From: David Fox d...@seereason.com To: miroslav.kar...@gmail.com Cc: Haskell Cafe haskell-cafe@haskell.org Sent: Wed, 09 Oct 2013 18:54 Subject: Re: [Haskell-cafe] Interfacing real-time stocks data API I would love to see Haskell bindings for this: https://us.etrade.com/active-trading/api On Tue, Oct 8, 2013 at 1:26 PM, Miro Karpis miroslav.kar...@gmail.comwrote: Please, did/does anybody tried to interface with Haskell some real-time stocks data API? If yes, please which one? So far I came down to ActveTick,... thanks, m. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Interfacing real-time stocks data API
There is also Interactive Brokers API, which used to be a lower cost alternative. On Wed, Oct 9, 2013 at 1:57 PM, miroslav.kar...@gmail.com wrote: Yes, I also like that one. Problem is that they give access only to US citizens and some limited countries. m. -Original Message- From: David Fox d...@seereason.com To: miroslav.kar...@gmail.com Cc: Haskell Cafe haskell-cafe@haskell.org Sent: Wed, 09 Oct 2013 18:54 Subject: Re: [Haskell-cafe] Interfacing real-time stocks data API I would love to see Haskell bindings for this: https://us.etrade.com/active-trading/api On Tue, Oct 8, 2013 at 1:26 PM, Miro Karpis miroslav.kar...@gmail.comwrote: Please, did/does anybody tried to interface with Haskell some real-time stocks data API? If yes, please which one? So far I came down to ActveTick,... thanks, m. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] Fwd: [Haskell-beginners] RankNTypes + ConstraintKinds to use Either as a union
(from thread:
http://www.haskell.org/pipermail/beginners/2013-October/012703.html)
Why type inference can't resolve this code?
{-# LANGUAGE RankNTypes, ConstraintKinds #-}
bar :: (Num a, Num b) = (forall c. Num c = c - c) - Either a b -
Either a b
bar f (Left a) = Left (f a)
bar f (Right b) = Right (f b)
bar' = bar (+ 2) -- This compiles ok
foo :: (tc a, tc b) = (forall c. tc c = c - c) - Either a b - Either
a b
foo f (Left a) = Left (f a)
foo f (Right b) = Right (f b)
foo' = foo (+ 2) -- This doesn't compile because foo' does not typecheck
-- Kim-Ee pointed out that this works:
type F tc a b = (tc a, tc b) = (forall c. tc c = c - c) - Either a b
- Either a b
foo' = (foo :: F Num a b) (+2)
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[Haskell-cafe] Case studies, step two
I want to thank everyone who provided pointers for the last question about this. They were a big help. We're now trying to narrow things down a bit. If you have either converted part of a business project from a language like ruby or python to Haskell, or have a business project that integrates Haskell with such a language and are willing to take a short survey about it, could you get back to me? Thanks ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] Interfacing real-time stocks data API
IB is not real-time though. On Wed, Oct 9, 2013 at 12:48 PM, Yuri de Wit yde...@gmail.com wrote: There is also Interactive Brokers API, which used to be a lower cost alternative. On Wed, Oct 9, 2013 at 1:57 PM, miroslav.kar...@gmail.com wrote: Yes, I also like that one. Problem is that they give access only to US citizens and some limited countries. m. -Original Message- From: David Fox d...@seereason.com To: miroslav.kar...@gmail.com Cc: Haskell Cafe haskell-cafe@haskell.org Sent: Wed, 09 Oct 2013 18:54 Subject: Re: [Haskell-cafe] Interfacing real-time stocks data API I would love to see Haskell bindings for this: https://us.etrade.com/active-trading/api On Tue, Oct 8, 2013 at 1:26 PM, Miro Karpis miroslav.kar...@gmail.comwrote: Please, did/does anybody tried to interface with Haskell some real-time stocks data API? If yes, please which one? So far I came down to ActveTick,... thanks, m. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe -- Cell: 1.630.740.8204 ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] RankNTypes + ConstraintKinds to use Either as a union
Thiago Negri wrote:
Why type inference can't resolve this code?
{-# LANGUAGE RankNTypes, ConstraintKinds #-}
bar :: (Num a, Num b) = (forall c. Num c = c - c) -Either a b -Either a b
bar f (Left a) = Left (f a)
bar f (Right b) = Right (f b)
bar' = bar (+ 2) -- This compiles ok
foo :: (tc a, tc b) = (forall c. tc c = c - c) - Either a b - Either a b
foo f (Left a) = Left (f a)
foo f (Right b) = Right (f b)
foo' = foo (+ 2) -- This doesn't compile because foo' does not typecheck
The type inference of the constraint fails because it is
ambiguous. Observe that not only bar (+2) compiles OK, but also
bar id. The function id :: c - c has no constraints attached, but
still fits for (forall c. Num c = c - c).
Let's look at the problematic foo'. What constraint would you think
GHC should infer for tc? Num? Why not the composition of Num and Read,
or Num and Show, or Num and any other set of constraints? Or perhaps
Fractional (because Fractional implies Num)? For
constraints, we get the implicit subtyping (a term well-typed with
constraints C is also well-typed with any bigger constraint set C',
or any constraint set C'' which implies C).
Synonyms and superclass constraints break the principal types.
So, inference is hopeless.
We got to help the type inference and tell which constraint we want.
For example,
newtype C ctx = C (forall c. ctx c = c - c)
foo :: (ctx a, ctx b) = C ctx - (forall c. ctx c = c - c) -
Either a b - Either a b
foo _ f (Left a) = Left (f a)
foo _ f (Right b) = Right (f b)
foo' = foo (undefined :: C Num) (+2)
Or, better
xyz :: (ctx a, ctx b) = C ctx - Either a b - Either a b
xyz (C f) (Left a) = Left (f a)
xyz (C f) (Right b) = Right (f b)
xyz' = xyz ((C (+2)) :: C Num)
xyz'' = xyz ((C (+2)) :: C Fractional)
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[Haskell-cafe] Suppressing HLint on pattern match of files
Hi, would like to disable 'Top-level binding with no type signature' In my test modules that are prefixed with Test. Is this possible ?? Thanks ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
