From defigueiredo at ucdavis.edu  Wed Nov 13 19:04:22 2019
From: defigueiredo at ucdavis.edu (Dimitri DeFigueiredo)
Date: Wed, 13 Nov 2019 11:04:22 -0800
Subject: [Haskell-beginners] What is this?
Message-ID: <f7fc8f17-369f-57fd-7d25-4f7ead213839@ucdavis.edu>

Hello,

Can anyone shed a light on the proper way to write the function below.
It looks pretty standard, but it's not clear to me what it is?

data Abortable res = Aborted | Executed res deriving Functor -- i.e. Maybe

abortableThroughEither :: Abortable (Either a b) ->  Either a (Abortable b)
abortableThroughEither Aborted              = Right Aborted
abortableThroughEither (Executed (Left  a)) = Left  a
abortableThroughEither (Executed (Right b)) = Right (Executed b)

Thanks!

Dimitri

-- 
2E45 D376 A744 C671 5100 A261 210B 8461 0FB0 CA1F



From toad3k at gmail.com  Wed Nov 13 19:20:12 2019
From: toad3k at gmail.com (David McBride)
Date: Wed, 13 Nov 2019 14:20:12 -0500
Subject: [Haskell-beginners] What is this?
In-Reply-To: <f7fc8f17-369f-57fd-7d25-4f7ead213839@ucdavis.edu>
References: <f7fc8f17-369f-57fd-7d25-4f7ead213839@ucdavis.edu>
Message-ID: <CAN+Tr40DyA1MrvMhmwCMg4QMqq-E=w=o9KPJShO6hA1Zp8PcQQ@mail.gmail.com>

It converts from Abortable (Either a b) to Either a (Abortable b).

My guess at their probable intent was that this operation tends to error
without aborting more often than it errors from an abort, so they put the
error on the outside so they can check the common case more easily.

On Wed, Nov 13, 2019 at 2:04 PM Dimitri DeFigueiredo <
defigueiredo at ucdavis.edu> wrote:

> Hello,
>
> Can anyone shed a light on the proper way to write the function below.
> It looks pretty standard, but it's not clear to me what it is?
>
> data Abortable res = Aborted | Executed res deriving Functor -- i.e. Maybe
>
> abortableThroughEither :: Abortable (Either a b) ->  Either a (Abortable b)
> abortableThroughEither Aborted              = Right Aborted
> abortableThroughEither (Executed (Left  a)) = Left  a
> abortableThroughEither (Executed (Right b)) = Right (Executed b)
>
> Thanks!
>
> Dimitri
>
> --
> 2E45 D376 A744 C671 5100 A261 210B 8461 0FB0 CA1F
>
>
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191113/67348072/attachment.html>

From tanuki at gmail.com  Wed Nov 13 20:46:44 2019
From: tanuki at gmail.com (Akhra Lief Gannon)
Date: Wed, 13 Nov 2019 12:46:44 -0800
Subject: [Haskell-beginners] What is this?
In-Reply-To: <CAN+Tr40DyA1MrvMhmwCMg4QMqq-E=w=o9KPJShO6hA1Zp8PcQQ@mail.gmail.com>
References: <f7fc8f17-369f-57fd-7d25-4f7ead213839@ucdavis.edu>
 <CAN+Tr40DyA1MrvMhmwCMg4QMqq-E=w=o9KPJShO6hA1Zp8PcQQ@mail.gmail.com>
Message-ID: <CAJoPsuAejvUWdt7mq0mMOkMmbr2Qs2QRS0XnCbzcqZ2zqFrwqQ@mail.gmail.com>

Incidentally, if you also derive Foldable and Traversable for Aborted,
abortableThroughEither is simply sequence.

On Wed, Nov 13, 2019 at 11:20 AM David McBride <toad3k at gmail.com> wrote:

> It converts from Abortable (Either a b) to Either a (Abortable b).
>
> My guess at their probable intent was that this operation tends to error
> without aborting more often than it errors from an abort, so they put the
> error on the outside so they can check the common case more easily.
>
> On Wed, Nov 13, 2019 at 2:04 PM Dimitri DeFigueiredo <
> defigueiredo at ucdavis.edu> wrote:
>
>> Hello,
>>
>> Can anyone shed a light on the proper way to write the function below.
>> It looks pretty standard, but it's not clear to me what it is?
>>
>> data Abortable res = Aborted | Executed res deriving Functor -- i.e. Maybe
>>
>> abortableThroughEither :: Abortable (Either a b) ->  Either a (Abortable
>> b)
>> abortableThroughEither Aborted              = Right Aborted
>> abortableThroughEither (Executed (Left  a)) = Left  a
>> abortableThroughEither (Executed (Right b)) = Right (Executed b)
>>
>> Thanks!
>>
>> Dimitri
>>
>> --
>> 2E45 D376 A744 C671 5100 A261 210B 8461 0FB0 CA1F
>>
>>
>> _______________________________________________
>> Beginners mailing list
>> Beginners at haskell.org
>> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>>
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191113/591834b6/attachment.html>

From Leonhard.Applis at protonmail.com  Fri Nov 15 11:36:03 2019
From: Leonhard.Applis at protonmail.com (Leonhard Applis)
Date: Fri, 15 Nov 2019 11:36:03 +0000
Subject: [Haskell-beginners] Expose every Function of a wrapped type
Message-ID: <8VyrlRTZwYrqqkI95kJ3UHQ41YSXFwhcqA4orOfVyau1ULCyCnVVkPI__Ya6rLaYFCUrVB3yM0IqT_l5NcCiMHhyfjsRg0S2xmxG3Cmvkq0=@protonmail.com>

Hi, 

I currently have a newtype definition of a typed Data.Map. 

newtype G = G Data.Map String Values 

I have done this because for my specific use-case, I can define G as a monoid and get some nice benefits. 

However, I find myself often just re-declaring functions of Data.Map and wrap/unwrap them in my Constructor G, such as 

singleton :: String -> Value -> G
singleton s v = G $ (Data.Map.singleton s v) 

I think I do not need to limit the scope of G's functionality, I basically want everything from Data.Map + Bonus , like my Monoid. 
Also I want G to be a specific Data.Map, there is never any other case where it's not a Map String Values. 

However, if I have 

type G2 = Data.Map String Values 

I cannot instance Monoid. 

So, I am very sure that I'm not the first person ever doing this. Is there a language extension providing what I want? Or is what i want "bad"?
Am I just missing a higher-order base function which does what I want?

best regards & thanks
Leonhard
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191115/904e640f/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: publickey - Leonhard.Applis at protonmail.com - 0x807FDDF3.asc
Type: application/pgp-keys
Size: 1843 bytes
Desc: not available
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191115/904e640f/attachment.key>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 477 bytes
Desc: OpenPGP digital signature
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191115/904e640f/attachment.sig>

From fa-ml at ariis.it  Fri Nov 15 14:11:12 2019
From: fa-ml at ariis.it (Francesco Ariis)
Date: Fri, 15 Nov 2019 15:11:12 +0100
Subject: [Haskell-beginners] Expose every Function of a wrapped type
In-Reply-To: <8VyrlRTZwYrqqkI95kJ3UHQ41YSXFwhcqA4orOfVyau1ULCyCnVVkPI__Ya6rLaYFCUrVB3yM0IqT_l5NcCiMHhyfjsRg0S2xmxG3Cmvkq0=@protonmail.com>
References: <8VyrlRTZwYrqqkI95kJ3UHQ41YSXFwhcqA4orOfVyau1ULCyCnVVkPI__Ya6rLaYFCUrVB3yM0IqT_l5NcCiMHhyfjsRg0S2xmxG3Cmvkq0=@protonmail.com>
Message-ID: <20191115141112.GA15508@x60s.casa>

Hello Leonardh,
    a couple of ideas:

On Fri, Nov 15, 2019 at 11:36:03AM +0000, Leonhard Applis wrote:
> I currently have a newtype definition of a typed Data.Map. 
> 
> newtype G = G Data.Map String Values 
> 
> [...]
> 
> However, if I have 
> 
> type G2 = Data.Map String Values 

`Map k v` is already an instance of `Monoid` (when `v` is an instance
of `Ord`), are you sure you need to write another one? If the answer
is "yes", you can write a small helper:

    withG :: (M.Map String a -> M.Map String a) -> G a -> G a
    withG mf (G m) = G $ mf m

or use GeneralizedNewtypeDeriving to ease some pain:

    {-# Language GeneralizedNewtypeDeriving #-}

    module Prova where

    import Data.Map as M
    import GHC.Exts

    newtype G a = G { unwrapG :: M.Map String a }
        deriving (Eq, Show, Functor, Foldable)

From traqueofziche at gmail.com  Sat Nov 16 23:46:51 2019
From: traqueofziche at gmail.com (=?UTF-8?B?6bKN5Yev5paH?=)
Date: Sat, 16 Nov 2019 15:46:51 -0800
Subject: [Haskell-beginners] Expose every Function of a wrapped type
In-Reply-To: <mailman.7.1573819201.5441.beginners@haskell.org>
References: <mailman.7.1573819201.5441.beginners@haskell.org>
Message-ID: <CAMjcG+HqBmMdHRUvu2jAET+vDsR=V8K51sK=61d3ryujgjH+8Q@mail.gmail.com>

Hi,

Have you considered using `Control.Lens.Wrapped` or `Control.Newtype`?
You'd have to move the wrapping/unwrapping bits to the sites in your code
at which you use underlying `Map` functions (quite repetitive), but it
could be easier than redefining all the functions you want (and definitely
easier than having to redefine a new one when you think of needing it?).

There's probably a canonical way to handle this sort of thing, but I can't
find it ATM. Good luck!

On Fri, Nov 15, 2019 at 5:00 AM <beginners-request at haskell.org> wrote:

> Send Beginners mailing list submissions to
>         beginners at haskell.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
>         http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
> or, via email, send a message with subject or body 'help' to
>         beginners-request at haskell.org
>
> You can reach the person managing the list at
>         beginners-owner at haskell.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Beginners digest..."
>
>
> Today's Topics:
>
>    1.  Expose every Function of a wrapped type (Leonhard Applis)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 15 Nov 2019 11:36:03 +0000
> From: Leonhard Applis <Leonhard.Applis at protonmail.com>
> To: "beginners at haskell.org" <beginners at haskell.org>
> Subject: [Haskell-beginners] Expose every Function of a wrapped type
> Message-ID:
>
> <8VyrlRTZwYrqqkI95kJ3UHQ41YSXFwhcqA4orOfVyau1ULCyCnVVkPI__Ya6rLaYFCUrVB3yM0IqT_l5NcCiMHhyfjsRg0S2xmxG3Cmvkq0=@
> protonmail.com>
>
> Content-Type: text/plain; charset="utf-8"
>
> Hi,
>
> I currently have a newtype definition of a typed Data.Map.
>
> newtype G = G Data.Map String Values
>
> I have done this because for my specific use-case, I can define G as a
> monoid and get some nice benefits.
>
> However, I find myself often just re-declaring functions of Data.Map and
> wrap/unwrap them in my Constructor G, such as
>
> singleton :: String -> Value -> G
> singleton s v = G $ (Data.Map.singleton s v)
>
> I think I do not need to limit the scope of G's functionality, I basically
> want everything from Data.Map + Bonus , like my Monoid.
> Also I want G to be a specific Data.Map, there is never any other case
> where it's not a Map String Values.
>
> However, if I have
>
> type G2 = Data.Map String Values
>
> I cannot instance Monoid.
>
> So, I am very sure that I'm not the first person ever doing this. Is there
> a language extension providing what I want? Or is what i want "bad"?
> Am I just missing a higher-order base function which does what I want?
>
> best regards & thanks
> Leonhard
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> http://mail.haskell.org/pipermail/beginners/attachments/20191115/904e640f/attachment-0001.html
> >
> -------------- next part --------------
> A non-text attachment was scrubbed...
> Name: publickey - Leonhard.Applis at protonmail.com - 0x807FDDF3.asc
> Type: application/pgp-keys
> Size: 1843 bytes
> Desc: not available
> URL: <
> http://mail.haskell.org/pipermail/beginners/attachments/20191115/904e640f/attachment-0001.key
> >
> -------------- next part --------------
> A non-text attachment was scrubbed...
> Name: signature.asc
> Type: application/pgp-signature
> Size: 477 bytes
> Desc: OpenPGP digital signature
> URL: <
> http://mail.haskell.org/pipermail/beginners/attachments/20191115/904e640f/attachment-0001.sig
> >
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
>
> ------------------------------
>
> End of Beginners Digest, Vol 137, Issue 2
> *****************************************
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191116/f4d9e485/attachment.html>

From alexander at chenjia.nl  Mon Nov 18 12:30:54 2019
From: alexander at chenjia.nl (Alexander Chen)
Date: Mon, 18 Nov 2019 13:30:54 +0100 (CET)
Subject: [Haskell-beginners] importing Data.Digits
Message-ID: <663503445.269564.1574080254193@ichabod.co-bxl>

Hi All,

This is my first 'post' not quite sure if I am doing it right.

I have a question about the importing of modules that are available on the Hackage.Haskell site:
http://hackage.haskell.org/package/digits

if I write this in my wordpad and then load it to GCI i get the following error:

chapter4.hs:1:1: error:
    Could not find module ‘Data.Digits’
    Perhaps you meant Data.Bits (from base-4.12.0.0)
    Use -v to see a list of the files searched for.
  |
1 | import Data.Digits   | ^^^^^^^^^^^^^^^^^^

However if I load Data.Char than it loads fine.

What am I doing wrong?

best,
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191118/0a2b2de4/attachment.html>

From toad3k at gmail.com  Mon Nov 18 13:11:30 2019
From: toad3k at gmail.com (David McBride)
Date: Mon, 18 Nov 2019 08:11:30 -0500
Subject: [Haskell-beginners] importing Data.Digits
In-Reply-To: <663503445.269564.1574080254193@ichabod.co-bxl>
References: <663503445.269564.1574080254193@ichabod.co-bxl>
Message-ID: <CAN+Tr42ngw5+cMFgb1DuknX4sVYMx2EdC_-eU=VtECw-_z=Y-A@mail.gmail.com>

This particular module comes from a separate package.  By default all
modules you use happen to be in the base package, which ships with ghc.  To
use other libraries you must make a proper project which tells ghc which
libraries you are using.  For example, the digits package uses this cabal
file at http://hackage.haskell.org/package/digits-0.3.1/digits.cabal

You can find more information about how to start a package from scratch
here https://www.haskell.org/cabal/users-guide/developing-packages.html

On Mon, Nov 18, 2019 at 7:31 AM Alexander Chen <alexander at chenjia.nl> wrote:

> Hi All,
>
> This is my first 'post' not quite sure if I am doing it right.
>
> I have a question about the importing of modules that are available on the
> Hackage.Haskell site:
> http://hackage.haskell.org/package/digits
>
> if I write this in my wordpad and then load it to GCI i get the following
> error:
>
>
> chapter4.hs:1:1: error:
>     Could not find module ‘Data.Digits’
>     Perhaps you meant Data.Bits (from base-4.12.0.0)
>     Use -v to see a list of the files searched for.
>   |
> 1 | import Data.Digits   | ^^^^^^^^^^^^^^^^^^
>
>
> However if I load Data.Char than it loads fine.
>
> What am I doing wrong?
>
> best,
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191118/e3c17e0d/attachment.html>

From Leonhard.Applis at protonmail.com  Mon Nov 18 20:42:22 2019
From: Leonhard.Applis at protonmail.com (Leonhard Applis)
Date: Mon, 18 Nov 2019 20:42:22 +0000
Subject: [Haskell-beginners] Export two modules from one.hs file?
Message-ID: <_QHLN6QYGGGjW3RwH0CJB2tIsuSBrKe3klqLJ45k_Kf-rUpFNV_XkUHLy38_V0e9byfWFK5nUDvfdSJ_xdoqhfx_XOwaeHUfzJz3q8QioSc=@protonmail.com>

Hey  All,

I currently want to make a module, which "truly" exposes 3 functions. However, there are more functions which I want to test.
I would like to export two modules from the same file, "ModuleToUse" and "ModuleOpen".
Then I can use ModuleToUse everywhere else, and ModuleOpen in the UnitTests.

I know I can declare ModuleOpen, and export only certain functions with ModuleToUse.
But I am not sure, if that is a smart / normal thing to do. In my case this would double my modules, and ... hence files?

What is the "real world" approach for this?

Thanks
Leonhard
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191118/6f8bf15d/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: publickey - Leonhard.Applis at protonmail.com - 0x807FDDF3.asc
Type: application/pgp-keys
Size: 1843 bytes
Desc: not available
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191118/6f8bf15d/attachment.key>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 477 bytes
Desc: OpenPGP digital signature
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191118/6f8bf15d/attachment.sig>

From Leonhard.Applis at protonmail.com  Mon Nov 18 22:22:01 2019
From: Leonhard.Applis at protonmail.com (Leonhard Applis)
Date: Mon, 18 Nov 2019 22:22:01 +0000
Subject: [Haskell-beginners] How to use the Data.Map inbuild Monoid
Message-ID: <J22L_DenEOy4uzUcjKrUq9cydX30XVPZtf784lfkyH-e_HWIVz5hOKKx7QHsUSd8NIkMvHucC9ZV_X4Yl735QrnqnymZmTm3IqMV1G-pvno=@protonmail.com>

Hello Francesco,

> `Map k v` is already an instance of `Monoid` (when `v` is an instance of `Ord`), are you sure you need to write another one?

Thanks for your answer!
My "Values" is a Monoid, however it seems that the Graph cannot properly be seen correctly as a Monoid

using mconcat does not (properly) work, meaning that <> is not correctly applied to the someMonoidsso instead of

type G = Map Text someMonoid
mconcat [gs]

I have to write:

foldr (Map.unionWith (<>)) Map.empty [gs]

This passes the tests.
Same Problem with
g1 <> g2  --(Does not work properly)
and
Map.unionWith (<>) g1 g2 --(Does work)

I have declared someMonoid myself, do I need to declare something special about it?
I feel like my G is messing up with <> being about him, or about someMonoid

A broken down piece of code is:

importData.MapasMap

dataSum=SumIntderiving (Eq,Show)

instanceSemigroupSumwhere
(<>) (Sum a) (Sum b)=Sum(a + b) 
instanceMonoidSumwhere
    mempty =Sum0

typeG=Map.MapStringSum

And to verify my problem:
GHCI > v = Map.singleton "A" (Sum 1)
GHCI > u = Map.singleton "A" (Sum 1)
GHCI> c= v <> u
GHCI> Map.lookup "A" c
Just (Sum 1)

but I want
Just (Sum 2)

thanks
Leonhard
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191118/1a748dcd/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: publickey - Leonhard.Applis at protonmail.com - 0x807FDDF3.asc
Type: application/pgp-keys
Size: 1843 bytes
Desc: not available
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191118/1a748dcd/attachment-0001.key>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 477 bytes
Desc: OpenPGP digital signature
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191118/1a748dcd/attachment-0001.sig>

From fa-ml at ariis.it  Mon Nov 18 22:23:52 2019
From: fa-ml at ariis.it (Francesco Ariis)
Date: Mon, 18 Nov 2019 23:23:52 +0100
Subject: [Haskell-beginners] Export two modules from one.hs file?
In-Reply-To: <_QHLN6QYGGGjW3RwH0CJB2tIsuSBrKe3klqLJ45k_Kf-rUpFNV_XkUHLy38_V0e9byfWFK5nUDvfdSJ_xdoqhfx_XOwaeHUfzJz3q8QioSc=@protonmail.com>
References: <_QHLN6QYGGGjW3RwH0CJB2tIsuSBrKe3klqLJ45k_Kf-rUpFNV_XkUHLy38_V0e9byfWFK5nUDvfdSJ_xdoqhfx_XOwaeHUfzJz3q8QioSc=@protonmail.com>
Message-ID: <20191118222039.GA9411@x60s.casa>

Hello Leonard,

On Mon, Nov 18, 2019 at 08:42:22PM +0000, Leonhard Applis wrote:
> I currently want to make a module, which "truly" exposes 3 functions.
> However, there are more functions which I want to test.
> I would like to export two modules from the same file, "ModuleToUse"
> and "ModuleOpen".

Unfortunately Haskell (rather, GHC) in its current incarnation does
not allow many-modules-per-single-file (which would indeed come quite
handy in cases like yours, in writing example code, etc.).

> What is the "real world" approach for this?

Have two modules, `Prova` and `Prova.Internal` (files:
`src/Prova.hs` and `src/Prova/Intenral.hs`).j

Does this answer your question?
-F

From simon.jakobi at googlemail.com  Mon Nov 18 22:48:06 2019
From: simon.jakobi at googlemail.com (Simon Jakobi)
Date: Mon, 18 Nov 2019 23:48:06 +0100
Subject: [Haskell-beginners] How to use the Data.Map inbuild Monoid
In-Reply-To: <J22L_DenEOy4uzUcjKrUq9cydX30XVPZtf784lfkyH-e_HWIVz5hOKKx7QHsUSd8NIkMvHucC9ZV_X4Yl735QrnqnymZmTm3IqMV1G-pvno=@protonmail.com>
References: <J22L_DenEOy4uzUcjKrUq9cydX30XVPZtf784lfkyH-e_HWIVz5hOKKx7QHsUSd8NIkMvHucC9ZV_X4Yl735QrnqnymZmTm3IqMV1G-pvno=@protonmail.com>
Message-ID: <CAGtp2Sh=s7JOgeBE9+=fB8KRpS-cHR4ZD0zPqFzF76dSiYXVDA@mail.gmail.com>

Hi Leonhard,

the monoidal-containers package should be interesting to you:

http://hackage.haskell.org/package/monoidal-containers

Cheers,
Simon

Am Mo., 18. Nov. 2019 um 23:22 Uhr schrieb Leonhard Applis
<Leonhard.Applis at protonmail.com>:
>
> Hello Francesco,
>
> > `Map k v` is already an instance of `Monoid` (when `v` is an instance of `Ord`), are you sure you need to write another one?
>
> Thanks for your answer!
> My "Values" is a Monoid, however it seems that the Graph cannot properly be seen correctly as a Monoid
>
> using mconcat does not (properly) work, meaning that <> is not correctly applied to the someMonoids
> so instead of
>
> type G = Map Text someMonoid
> mconcat [gs]
>
> I have to write:
>
> foldr (Map.unionWith (<>)) Map.empty [gs]
>
> This passes the tests.
> Same Problem with
> g1 <> g2  --(Does not work properly)
> and
> Map.unionWith (<>) g1 g2 --(Does work)
>
> I have declared someMonoid myself, do I need to declare something special about it?
> I feel like my G is messing up with <> being about him, or about someMonoid
>
> A broken down piece of code is:
>
> import Data.Map as Map
>
> data Sum = Sum Int deriving (Eq,Show)
>
> instance Semigroup Sum where
>     (<>) (Sum a) (Sum b)= Sum(a + b)
> instance Monoid Sum where
>     mempty = Sum 0
>
> type G = Map.Map String Sum
>
> And to verify my problem:
> GHCI > v = Map.singleton "A" (Sum 1)
> GHCI > u = Map.singleton "A" (Sum 1)
> GHCI> c= v <> u
> GHCI> Map.lookup "A" c
> Just (Sum 1)
>
> but I want
> Just (Sum 2)
>
> thanks
> Leonhard
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners

From juncheng_hsk at outlook.com  Fri Nov 22 11:41:12 2019
From: juncheng_hsk at outlook.com (juncheng_hsk at outlook.com)
Date: Fri, 22 Nov 2019 11:41:12 +0000
Subject: [Haskell-beginners] Configuration of Environment
Message-ID: <CY4PR11MB1783EA312A042720B02EB273C5490@CY4PR11MB1783.namprd11.prod.outlook.com>

Hi All,

I’m a newcomer to Haskell and mailing list, so I am not sure if my question is proper.

I use notepad++ to learn Haskell now. Are there any suggestions or conventions which can help me learn Haskell?

Best regards,
Juncheng
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191122/490a8625/attachment.html>

From Leonhard.Applis at protonmail.com  Fri Nov 22 14:13:15 2019
From: Leonhard.Applis at protonmail.com (Leonhard Applis)
Date: Fri, 22 Nov 2019 14:13:15 +0000
Subject: [Haskell-beginners] Configuration of Environment
Message-ID: <LgL8bBwW97tZNUL-ak1sYGEBXhXMVh4V4aZX-D-SoKvp08-ZNEzNGc-7uWtyzy9hE69cBoGAGEdT603rehEgzw333NuVenjVsN1YJ8RwzdA=@protonmail.com>

> Hi All,
> 

> I’m a newcomer to Haskell and mailing list, so I am not sure if my question is proper.
> 

> I use notepad++ to learn Haskell now. Are there any suggestions or conventions which can help me learn Haskell?
> 

> Best regards,
> Juncheng

Hi Juncheng, 


I think for learning "code", as in writing nice code, get yourself the Hlinter [1] running. 

It really spots great improvements and some very haskelly ways. 

For Learning purposes I would suggest that you first "try it your way" step by step, and check every step with hlint. 

So: fun1 -> Hlint -> fun2 -> Hlint 


Additionally you might want to enable a spell-checker (like, a normal one, for english). 


Last thing you might find very useful is a local Hoogle [2] install.
It's amazingly convenient if you want to know, e.g. the function which gives a length of a list, but you don't remember if it was len, length, size, count ... 

So you just search for [a] -> Int and voila. 

Second Hoogle can help you find similar functions to what you are currently building, often you are implementing something that is somewhere as a higher order function already. 


best regards,
Leonhard



[1] Hlint: http://hackage.haskell.org/package/hlint
[2] Hoogle: http://hackage.haskell.org/package/hoogle
-------------- next part --------------
A non-text attachment was scrubbed...
Name: publickey - Leonhard.Applis at protonmail.com - 0x807FDDF3.asc
Type: application/pgp-keys
Size: 1843 bytes
Desc: not available
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191122/582afdf3/attachment.key>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 477 bytes
Desc: OpenPGP digital signature
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191122/582afdf3/attachment.sig>

From alexander at chenjia.nl  Sat Nov 23 18:38:03 2019
From: alexander at chenjia.nl (Alexander Chen)
Date: Sat, 23 Nov 2019 19:38:03 +0100 (CET)
Subject: [Haskell-beginners] list doesn't end
Message-ID: <1722033790.317238.1574534283773@ichabod.co-bxl>

Hi,

I am doing some further learning with euler now in Haskell instead of Julia. But I am getting something strange.

[x+y+z | x <- a2, y <- b3,  z <- c4, (x+y+z) < 50]

a2, b3, c4 are all finite lists derived from the lazy list of the primes package. the output is:

[28,47,33,49

this is not a typo it is still calculating hence the missing bracket (for the last couple of hours, when to a christmas fair in between). The only thing is that, this should be the answer:

[28,47,33,49] 

so it should be done but its not. what am I doing wrong?

best,
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191123/77520139/attachment.html>

From ollie at ocharles.org.uk  Sat Nov 23 18:42:05 2019
From: ollie at ocharles.org.uk (Oliver Charles)
Date: Sat, 23 Nov 2019 18:42:05 +0000
Subject: [Haskell-beginners] list doesn't end
In-Reply-To: <1722033790.317238.1574534283773@ichabod.co-bxl>
References: <1722033790.317238.1574534283773@ichabod.co-bxl>
Message-ID: <CAGRp5Rk0RwSe39n8zx+=tm61QrvWTZvgSHPs5FgwgFt3LvKmxA@mail.gmail.com>

How big are those lists? GHC will not be able to work out x+y+z < 50 will
never be true again, it will have to exhaustively consider *every*
combination.

On Sat, 23 Nov 2019, 6:38 pm Alexander Chen, <alexander at chenjia.nl> wrote:

> Hi,
>
> I am doing some further learning with euler now in Haskell instead of
> Julia. But I am getting something strange.
>
> [x+y+z | x <- a2, y <- b3,  z <- c4, (x+y+z) < 50]
>
> a2, b3, c4 are all finite lists derived from the lazy list of the primes
> package. the output is:
>
> [28,47,33,49
>
> this is not a typo it is still calculating hence the missing bracket (for
> the last couple of hours, when to a christmas fair in between). The only
> thing is that, this should be the answer:
>
> [28,47,33,49]
>
>
> so it should be done but its not. what am I doing wrong?
>
> best,
>
>
>
>
>
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191123/151c94ae/attachment.html>

From fa-ml at ariis.it  Sat Nov 23 19:05:32 2019
From: fa-ml at ariis.it (Francesco Ariis)
Date: Sat, 23 Nov 2019 20:05:32 +0100
Subject: [Haskell-beginners] list doesn't end
In-Reply-To: <1722033790.317238.1574534283773@ichabod.co-bxl>
References: <1722033790.317238.1574534283773@ichabod.co-bxl>
Message-ID: <20191123190532.GA659@x60s.casa>

Hello Alexander,

On Sat, Nov 23, 2019 at 07:38:03PM +0100, Alexander Chen wrote:
> Hi,
> 
> I am doing some further learning with euler now in Haskell instead of Julia. But I am getting something strange.
> 
> [x+y+z | x <- a2, y <- b3,  z <- c4, (x+y+z) < 50]
> 
> a2, b3, c4 are all finite lists derived from the lazy list of the primes package. the output is:
> 
> [28,47,33,49

    λ> :m Data.Numbers.Primes
    λ> let a = take 100 primes
    λ> length [x+y+x | x <- a, y <- a, z <- a, (x+y+z) < 50]
    942

I suspect one in [a2, b3, c4] is infinite (or very very long). Can you
paste the whole calculation?
-F

From alexander at chenjia.nl  Sun Nov 24 16:10:17 2019
From: alexander at chenjia.nl (Alexander Chen)
Date: Sun, 24 Nov 2019 17:10:17 +0100 (CET)
Subject: [Haskell-beginners] list doesn't end
In-Reply-To: <20191123190532.GA659@x60s.casa>
References: <1722033790.317238.1574534283773@ichabod.co-bxl>
 <20191123190532.GA659@x60s.casa>
Message-ID: <1726437853.349004.1574611817399@ichabod.co-bxl>

Hi Francesco,

length a2 = 7072
length b3 = 7072
length c4 = 82

I suspect its the first two that get it into trouble. Is is 7072*7072*82 = 41014081088 permutations, 100*3 = 1000000.

So I am guessing that this is not the fix to the euler problem....

best.

November 23, 2019 8:05:32 PM CET Francesco Ariis <fa-ml at ariis.it> wrote:Hello Alexander,

On Sat, Nov 23, 2019 at 07:38:03PM +0100, Alexander Chen wrote:
> Hi,
> 
> I am doing some further learning with euler now in Haskell instead of Julia.
But I am getting something strange.
> 
> [x+y+z | x <- a2, y <- b3,  z <- c4, (x+y+z) < 50]
> 
> a2, b3, c4 are all finite lists derived from the lazy list of the primes
package. the output is:
> 
> [28,47,33,49

    λ> :m Data.Numbers.Primes
    λ> let a = take 100 primes
    λ> length [x+y+x | x <- a, y <- a, z <- a, (x+y+z) < 50]
    942

I suspect one in [a2, b3, c4] is infinite (or very very long). Can you
paste the whole calculation?
-F
_______________________________________________
Beginners mailing list
Beginners at haskell.org
http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191124/38868b3f/attachment.html>

From fa-ml at ariis.it  Sun Nov 24 18:19:51 2019
From: fa-ml at ariis.it (Francesco Ariis)
Date: Sun, 24 Nov 2019 19:19:51 +0100
Subject: [Haskell-beginners] list doesn't end
In-Reply-To: <1726437853.349004.1574611817399@ichabod.co-bxl>
References: <1722033790.317238.1574534283773@ichabod.co-bxl>
 <20191123190532.GA659@x60s.casa>
 <1726437853.349004.1574611817399@ichabod.co-bxl>
Message-ID: <20191124181951.GB3552@x60s.casa>

On Sun, Nov 24, 2019 at 05:10:17PM +0100, Alexander Chen wrote:
> Hi Francesco,
> 
> length a2 = 7072
> length b3 = 7072
> length c4 = 82
> 
> I suspect its the first two that get it into trouble. Is is 7072*7072*82 = 41014081088 permutations, 100*3 = 1000000.
> 
> So I am guessing that this is not the fix to the euler problem....

If `x+y+z` need to be <50, and the three are primes, I am puzzled to see
such lengths!
Which problem is it?

From alexander at chenjia.nl  Mon Nov 25 07:55:17 2019
From: alexander at chenjia.nl (Alexander Chen)
Date: Mon, 25 Nov 2019 08:55:17 +0100 (CET)
Subject: [Haskell-beginners] list doesn't end
In-Reply-To: <20191124181951.GB3552@x60s.casa>
References: <1722033790.317238.1574534283773@ichabod.co-bxl>
 <20191123190532.GA659@x60s.casa>
 <1726437853.349004.1574611817399@ichabod.co-bxl>
 <20191124181951.GB3552@x60s.casa>
Message-ID: <643030919.375007.1574668517628@ichabod.co-bxl>

Hi Francesco,

Their is a ^2, ^3, ^4 in the lists, respectively.

see https://projecteuler.net/problem=87

best,

November 24, 2019 7:19:51 PM CET Francesco Ariis <fa-ml at ariis.it> wrote:On Sun, Nov 24, 2019 at 05:10:17PM +0100, Alexander Chen wrote:
> Hi Francesco,
> 
> length a2 = 7072
> length b3 = 7072
> length c4 = 82
> 
> I suspect its the first two that get it into trouble. Is is 7072*7072*82 =
41014081088 permutations, 100*3 = 1000000.
> 
> So I am guessing that this is not the fix to the euler problem....

If `x+y+z` need to be <50, and the three are primes, I am puzzled to see
such lengths!
Which problem is it?
_______________________________________________
Beginners mailing list
Beginners at haskell.org
http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191125/6de973df/attachment.html>

From fa-ml at ariis.it  Mon Nov 25 13:20:24 2019
From: fa-ml at ariis.it (Francesco Ariis)
Date: Mon, 25 Nov 2019 14:20:24 +0100
Subject: [Haskell-beginners] list doesn't end
In-Reply-To: <643030919.375007.1574668517628@ichabod.co-bxl>
References: <1722033790.317238.1574534283773@ichabod.co-bxl>
 <20191123190532.GA659@x60s.casa>
 <1726437853.349004.1574611817399@ichabod.co-bxl>
 <20191124181951.GB3552@x60s.casa>
 <643030919.375007.1574668517628@ichabod.co-bxl>
Message-ID: <20191125132024.GA16954@x60s.casa>

On Mon, Nov 25, 2019 at 08:55:17AM +0100, Alexander Chen wrote:
> Hi Francesco,
> 
> Their is a ^2, ^3, ^4 in the lists, respectively.
> 
> see https://projecteuler.net/problem=87

This runs reasonably fast even on my old 32bit machine:

    import qualified Data.Set as S
    import Data.Numbers.Primes

    sol72 :: Integer -> Int
    sol72 l = S.size . S.fromList $
                [(x+y+z) | x <- p2, y <- p3, z <- p4, x+y+z < l]
        where
              f :: Integer -> [Integer]
              f n = takeWhile (< l) $ map (^n) primes

              p2, p3, p4 :: [Integer]
              p2 = f 2
              p3 = f 3
              p4 = f 4

    λ> sol72 (50 * 10^6)
    1097343

Notice how the lengths for lists p2, p3 and p4 are actually 908, 73
and 23!
-F


From Leonhard.Applis at protonmail.com  Thu Nov 28 14:15:27 2019
From: Leonhard.Applis at protonmail.com (Leonhard Applis)
Date: Thu, 28 Nov 2019 14:15:27 +0000
Subject: [Haskell-beginners] Providing Haskell Libraries wrapped for other
	Languages
Message-ID: <GWMEmGPietL5BGMOXNm_vOI1zYWXem1x6GOctodu3ftdJVurBPz36E5Jjq_lzGz7XC4t1CNeY-XajQCrh0j4NKVFXBTTGG4pBmJL6bh4U4s=@protonmail.com>

Hi, 
I am currently writing a small library. I will provide a small web-api for it, however I have some colleagues who neither have experience in haskell, nor in web-dev. 
Also they maybe want to produce programs using my library without internet / docker / etc. 

So in addition I'd like to provide the library "wrapped" for other languages, especially python, but maybe java as well. 
These wrappers should do nothing except invoking their pardons on the library, and should somewhat contain the library. 

What is the common way to do this? 
I've seen "hyphen" as a super heavyweight solution, and I've seen people starting the haskell library listening on system-pipes. 
I don't feel that these are the "best" solutions, atleast for my intention. 

best regards
Leonhard
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191128/38f52f24/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: publickey - Leonhard.Applis at protonmail.com - 0x807FDDF3.asc
Type: application/pgp-keys
Size: 1843 bytes
Desc: not available
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191128/38f52f24/attachment.key>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 477 bytes
Desc: OpenPGP digital signature
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191128/38f52f24/attachment.sig>

From simon.jakobi at googlemail.com  Thu Nov 28 15:43:30 2019
From: simon.jakobi at googlemail.com (Simon Jakobi)
Date: Thu, 28 Nov 2019 16:43:30 +0100
Subject: [Haskell-beginners] Providing Haskell Libraries wrapped for
	other Languages
In-Reply-To: <GWMEmGPietL5BGMOXNm_vOI1zYWXem1x6GOctodu3ftdJVurBPz36E5Jjq_lzGz7XC4t1CNeY-XajQCrh0j4NKVFXBTTGG4pBmJL6bh4U4s=@protonmail.com>
References: <GWMEmGPietL5BGMOXNm_vOI1zYWXem1x6GOctodu3ftdJVurBPz36E5Jjq_lzGz7XC4t1CNeY-XajQCrh0j4NKVFXBTTGG4pBmJL6bh4U4s=@protonmail.com>
Message-ID: <CAGtp2ShEN3HqQb2GAsPniZecStDSkqunUOz=tG7oU3TAtRXTAw@mail.gmail.com>

Hi Leonhard,

I don't have any experience with calling Haskell from other languages
but I am aware of this project:

https://github.com/nh2/call-haskell-from-anything

I hope it's useful to you.

Cheers,
Simon

Am Do., 28. Nov. 2019 um 15:15 Uhr schrieb Leonhard Applis
<Leonhard.Applis at protonmail.com>:
>
> Hi,
>
> I am currently writing a small library.
> I will provide a small web-api for it, however I have some colleagues who neither have experience in haskell, nor in web-dev.
> Also they maybe want to produce programs using my library without internet / docker / etc.
>
> So in addition I'd like to provide the library "wrapped" for other languages, especially python, but maybe java as well.
> These wrappers should do nothing except invoking their pardons on the library, and should somewhat contain the library.
>
> What is the common way to do this?
>
>
>
> I've seen "hyphen" as a super heavyweight solution, and I've seen people starting the haskell library listening on system-pipes.
> I don't feel that these are the "best" solutions, atleast for my intention.
>
> best regards
> Leonhard
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners

From frederic-emmanuel.picca at synchrotron-soleil.fr  Fri Nov 29 10:55:35 2019
From: frederic-emmanuel.picca at synchrotron-soleil.fr (PICCA Frederic-Emmanuel)
Date: Fri, 29 Nov 2019 10:55:35 +0000
Subject: [Haskell-beginners] strange error inside a case
Message-ID: <A2A20EC3B8560D408356CAC2FC148E53017D83AB1A@SUN-DAG3.synchrotron-soleil.fr>

Hello, I aheve some code whcih look like this

thumbnail' :: (MonadIO m, MonadReader Beamline m, MonadThrow m) => ThumbnailInput -> m ()
thumbnail' (ThumbnailInput col) = do
  cwd <- toResultsPath "thumbnail" col
  let shakeFiles' =  cwd </> $(mkRelDir ".shake/")
  let shakeReport' = shakeFiles' </> $(mkRelFile "report.html")

  liftIO $ shake shakeOptions{ shakeFiles=fromAbsDir shakeFiles'
                             , shakeReport=[fromAbsFile shakeReport']
                             , shakeVerbosity=Diagnostic
                             } $ do
    let uploaded = fromAbsFile $ cwd </> $(mkRelFile "thumbnail.uploaded")

    want [uploaded]

    -- (Rule 1) merge the image files
    uploaded %> \_out -> do
      -- need [xml]
      masters <- liftIO $ expectedInputFiles col
      liftIO $ hdf2mergedcbf' (head masters) 1 1 
      liftIO $ case col of
        (SomeDataCollection SCollect SHdf5 _)          -> hdf2mergedcbf' (head masters) 1 1
        (SomeDataCollection SCollect SHdf5' _)         -> undefined -- hdf2mergedcbf' (head masters) 1 1
        (SomeDataCollection SCaracterization SHdf5 _)  -> undefined
        (SomeDataCollection SCaracterization SHdf5' _) -> undefined
        _                                              -> error "show not arrive here !!!"

      -- hdf2mergedcbf
      -- command [] "touch" [uploaded]
      return ()


When I try to compile it, it give me this error

    • Couldn't match type ‘a0’ with ‘()’
        ‘a0’ is untouchable
          inside the constraints: f ~ 'ISPyB.DataCollection.Hdf5
          bound by a pattern with constructor:
                     SHdf5 :: SCollectSourceFormat 'ISPyB.DataCollection.Hdf5,
                   in a case alternative
          at src/Thumbnail.hs:180:38-42
      Expected type: IO a0
        Actual type: IO ()
    • In the expression: hdf2mergedcbf' (head masters) 1 1
      In a case alternative:
          (SomeDataCollection SCollect SHdf5 _)
            -> hdf2mergedcbf' (head masters) 1 1
      In the second argument of ‘($)’, namely
        ‘case col of
           (SomeDataCollection SCollect SHdf5 _)
             -> hdf2mergedcbf' (head masters) 1 1
           (SomeDataCollection SCollect SHdf5' _) -> undefined
           (SomeDataCollection SCaracterization SHdf5 _) -> undefined
           (SomeDataCollection SCaracterization SHdf5' _) -> undefined
           _ -> error "show not arrive here !!!"’
    |
180 |         (SomeDataCollection SCollect SHdf5 _)          -> hdf2mergedcbf' (head masters) 1 1
    |                                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


What I do not understand is how to fix this since it seems that

  liftIO $ hdf2mergedcbf' (head masters) 1 1  works out of the case

thanks for your help

Frederic

From sylvain at haskus.fr  Fri Nov 29 11:29:23 2019
From: sylvain at haskus.fr (Sylvain Henry)
Date: Fri, 29 Nov 2019 12:29:23 +0100
Subject: [Haskell-beginners] strange error inside a case
In-Reply-To: <A2A20EC3B8560D408356CAC2FC148E53017D83AB1A@SUN-DAG3.synchrotron-soleil.fr>
References: <A2A20EC3B8560D408356CAC2FC148E53017D83AB1A@SUN-DAG3.synchrotron-soleil.fr>
Message-ID: <7c062774-ff78-569a-fba5-543eccf7cecd@haskus.fr>

Hello,

What is the type of hdf2mergedcbf' ?

Does it work if you write `void (hdf2mergedcbf' (head masters) 1 1)` ?


On 29/11/2019 11:55, PICCA Frederic-Emmanuel wrote:
> Hello, I aheve some code whcih look like this
>
> thumbnail' :: (MonadIO m, MonadReader Beamline m, MonadThrow m) => ThumbnailInput -> m ()
> thumbnail' (ThumbnailInput col) = do
>    cwd <- toResultsPath "thumbnail" col
>    let shakeFiles' =  cwd </> $(mkRelDir ".shake/")
>    let shakeReport' = shakeFiles' </> $(mkRelFile "report.html")
>
>    liftIO $ shake shakeOptions{ shakeFiles=fromAbsDir shakeFiles'
>                               , shakeReport=[fromAbsFile shakeReport']
>                               , shakeVerbosity=Diagnostic
>                               } $ do
>      let uploaded = fromAbsFile $ cwd </> $(mkRelFile "thumbnail.uploaded")
>
>      want [uploaded]
>
>      -- (Rule 1) merge the image files
>      uploaded %> \_out -> do
>        -- need [xml]
>        masters <- liftIO $ expectedInputFiles col
>        liftIO $ hdf2mergedcbf' (head masters) 1 1
>        liftIO $ case col of
>          (SomeDataCollection SCollect SHdf5 _)          -> hdf2mergedcbf' (head masters) 1 1
>          (SomeDataCollection SCollect SHdf5' _)         -> undefined -- hdf2mergedcbf' (head masters) 1 1
>          (SomeDataCollection SCaracterization SHdf5 _)  -> undefined
>          (SomeDataCollection SCaracterization SHdf5' _) -> undefined
>          _                                              -> error "show not arrive here !!!"
>
>        -- hdf2mergedcbf
>        -- command [] "touch" [uploaded]
>        return ()
>
>
> When I try to compile it, it give me this error
>
>      • Couldn't match type ‘a0’ with ‘()’
>          ‘a0’ is untouchable
>            inside the constraints: f ~ 'ISPyB.DataCollection.Hdf5
>            bound by a pattern with constructor:
>                       SHdf5 :: SCollectSourceFormat 'ISPyB.DataCollection.Hdf5,
>                     in a case alternative
>            at src/Thumbnail.hs:180:38-42
>        Expected type: IO a0
>          Actual type: IO ()
>      • In the expression: hdf2mergedcbf' (head masters) 1 1
>        In a case alternative:
>            (SomeDataCollection SCollect SHdf5 _)
>              -> hdf2mergedcbf' (head masters) 1 1
>        In the second argument of ‘($)’, namely
>          ‘case col of
>             (SomeDataCollection SCollect SHdf5 _)
>               -> hdf2mergedcbf' (head masters) 1 1
>             (SomeDataCollection SCollect SHdf5' _) -> undefined
>             (SomeDataCollection SCaracterization SHdf5 _) -> undefined
>             (SomeDataCollection SCaracterization SHdf5' _) -> undefined
>             _ -> error "show not arrive here !!!"’
>      |
> 180 |         (SomeDataCollection SCollect SHdf5 _)          -> hdf2mergedcbf' (head masters) 1 1
>      |                                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>
> What I do not understand is how to fix this since it seems that
>
>    liftIO $ hdf2mergedcbf' (head masters) 1 1  works out of the case
>
> thanks for your help
>
> Frederic
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners

From traqueofziche at gmail.com  Fri Nov 29 15:11:55 2019
From: traqueofziche at gmail.com (=?UTF-8?B?6bKN5Yev5paH?=)
Date: Fri, 29 Nov 2019 07:11:55 -0800
Subject: [Haskell-beginners] Providing Haskell Libraries wrapped for
	other Languages
In-Reply-To: <mailman.5.1575028802.24378.beginners@haskell.org>
References: <mailman.5.1575028802.24378.beginners@haskell.org>
Message-ID: <CAMjcG+E8ZP1WRRpDCXm4urtfv21kW5_4n03nW9gettztgF2YwA@mail.gmail.com>

Hi,

Have you looked into Apache thrift (
https://thrift.apache.org
)? You’d provide interface definitions and the thrift compiler generates
client/server code from those. If the overhead of that is intolerable and
you really want to call functions “directly”, you could try exporting
haskell functions to c and then writing bindings to that for your language,
e.g. using the python c api or JNI. I’m just not sure how one’s supposed to
ensure initialization of the haskell runtime in any case.

Good luck

On Fri, Nov 29, 2019 at 5:00 AM <beginners-request at haskell.org> wrote:

> Send Beginners mailing list submissions to
>         beginners at haskell.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
>         http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
> or, via email, send a message with subject or body 'help' to
>         beginners-request at haskell.org
>
> You can reach the person managing the list at
>         beginners-owner at haskell.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of Beginners digest..."
>
>
> Today's Topics:
>
>    1.  Providing Haskell Libraries wrapped for other    Languages
>       (Leonhard Applis)
>    2. Re:  Providing Haskell Libraries wrapped for      other Languages
>       (Simon Jakobi)
>    3.  strange error inside a case (PICCA Frederic-Emmanuel)
>    4. Re:  strange error inside a case (Sylvain Henry)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 28 Nov 2019 14:15:27 +0000
> From: Leonhard Applis <Leonhard.Applis at protonmail.com>
> To: "beginners at haskell.org" <beginners at haskell.org>
> Subject: [Haskell-beginners] Providing Haskell Libraries wrapped for
>         other   Languages
> Message-ID:
>
> <GWMEmGPietL5BGMOXNm_vOI1zYWXem1x6GOctodu3ftdJVurBPz36E5Jjq_lzGz7XC4t1CNeY-XajQCrh0j4NKVFXBTTGG4pBmJL6bh4U4s=@
> protonmail.com>
>
> Content-Type: text/plain; charset="utf-8"
>
> Hi,
> I am currently writing a small library. I will provide a small web-api for
> it, however I have some colleagues who neither have experience in haskell,
> nor in web-dev.
> Also they maybe want to produce programs using my library without internet
> / docker / etc.
>
> So in addition I'd like to provide the library "wrapped" for other
> languages, especially python, but maybe java as well.
> These wrappers should do nothing except invoking their pardons on the
> library, and should somewhat contain the library.
>
> What is the common way to do this?
> I've seen "hyphen" as a super heavyweight solution, and I've seen people
> starting the haskell library listening on system-pipes.
> I don't feel that these are the "best" solutions, atleast for my
> intention.
>
> best regards
> Leonhard
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: <
> http://mail.haskell.org/pipermail/beginners/attachments/20191128/38f52f24/attachment-0001.html
> >
> -------------- next part --------------
> A non-text attachment was scrubbed...
> Name: publickey - Leonhard.Applis at protonmail.com - 0x807FDDF3.asc
> Type: application/pgp-keys
> Size: 1843 bytes
> Desc: not available
> URL: <
> http://mail.haskell.org/pipermail/beginners/attachments/20191128/38f52f24/attachment-0001.key
> >
> -------------- next part --------------
> A non-text attachment was scrubbed...
> Name: signature.asc
> Type: application/pgp-signature
> Size: 477 bytes
> Desc: OpenPGP digital signature
> URL: <
> http://mail.haskell.org/pipermail/beginners/attachments/20191128/38f52f24/attachment-0001.sig
> >
>
> ------------------------------
>
> Message: 2
> Date: Thu, 28 Nov 2019 16:43:30 +0100
> From: Simon Jakobi <simon.jakobi at googlemail.com>
> To: Leonhard Applis <Leonhard.Applis at protonmail.com>,  The
>         Haskell-Beginners Mailing List - Discussion of primarily
>         beginner-level topics related to Haskell <beginners at haskell.org>
> Subject: Re: [Haskell-beginners] Providing Haskell Libraries wrapped
>         for     other Languages
> Message-ID:
>         <CAGtp2ShEN3HqQb2GAsPniZecStDSkqunUOz=
> tG7oU3TAtRXTAw at mail.gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
> Hi Leonhard,
>
> I don't have any experience with calling Haskell from other languages
> but I am aware of this project:
>
> https://github.com/nh2/call-haskell-from-anything
>
> I hope it's useful to you.
>
> Cheers,
> Simon
>
> Am Do., 28. Nov. 2019 um 15:15 Uhr schrieb Leonhard Applis
> <Leonhard.Applis at protonmail.com>:
> >
> > Hi,
> >
> > I am currently writing a small library.
> > I will provide a small web-api for it, however I have some colleagues
> who neither have experience in haskell, nor in web-dev.
> > Also they maybe want to produce programs using my library without
> internet / docker / etc.
> >
> > So in addition I'd like to provide the library "wrapped" for other
> languages, especially python, but maybe java as well.
> > These wrappers should do nothing except invoking their pardons on the
> library, and should somewhat contain the library.
> >
> > What is the common way to do this?
> >
> >
> >
> > I've seen "hyphen" as a super heavyweight solution, and I've seen people
> starting the haskell library listening on system-pipes.
> > I don't feel that these are the "best" solutions, atleast for my
> intention.
> >
> > best regards
> > Leonhard
> > _______________________________________________
> > Beginners mailing list
> > Beginners at haskell.org
> > http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
>
> ------------------------------
>
> Message: 3
> Date: Fri, 29 Nov 2019 10:55:35 +0000
> From: PICCA Frederic-Emmanuel
>         <frederic-emmanuel.picca at synchrotron-soleil.fr>
> To: "The Haskell-Beginners Mailing List - Discussion of primarily
>         beginner-level topics related to Haskell" <beginners at haskell.org>
> Subject: [Haskell-beginners] strange error inside a case
> Message-ID:
>         <
> A2A20EC3B8560D408356CAC2FC148E53017D83AB1A at SUN-DAG3.synchrotron-soleil.fr>
>
> Content-Type: text/plain; charset="Windows-1252"
>
> Hello, I aheve some code whcih look like this
>
> thumbnail' :: (MonadIO m, MonadReader Beamline m, MonadThrow m) =>
> ThumbnailInput -> m ()
> thumbnail' (ThumbnailInput col) = do
>   cwd <- toResultsPath "thumbnail" col
>   let shakeFiles' =  cwd </> $(mkRelDir ".shake/")
>   let shakeReport' = shakeFiles' </> $(mkRelFile "report.html")
>
>   liftIO $ shake shakeOptions{ shakeFiles=fromAbsDir shakeFiles'
>                              , shakeReport=[fromAbsFile shakeReport']
>                              , shakeVerbosity=Diagnostic
>                              } $ do
>     let uploaded = fromAbsFile $ cwd </> $(mkRelFile "thumbnail.uploaded")
>
>     want [uploaded]
>
>     -- (Rule 1) merge the image files
>     uploaded %> \_out -> do
>       -- need [xml]
>       masters <- liftIO $ expectedInputFiles col
>       liftIO $ hdf2mergedcbf' (head masters) 1 1
>       liftIO $ case col of
>         (SomeDataCollection SCollect SHdf5 _)          -> hdf2mergedcbf'
> (head masters) 1 1
>         (SomeDataCollection SCollect SHdf5' _)         -> undefined --
> hdf2mergedcbf' (head masters) 1 1
>         (SomeDataCollection SCaracterization SHdf5 _)  -> undefined
>         (SomeDataCollection SCaracterization SHdf5' _) -> undefined
>         _                                              -> error "show not
> arrive here !!!"
>
>       -- hdf2mergedcbf
>       -- command [] "touch" [uploaded]
>       return ()
>
>
> When I try to compile it, it give me this error
>
>     • Couldn't match type ‘a0’ with ‘()’
>         ‘a0’ is untouchable
>           inside the constraints: f ~ 'ISPyB.DataCollection.Hdf5
>           bound by a pattern with constructor:
>                      SHdf5 :: SCollectSourceFormat
> 'ISPyB.DataCollection.Hdf5,
>                    in a case alternative
>           at src/Thumbnail.hs:180:38-42
>       Expected type: IO a0
>         Actual type: IO ()
>     • In the expression: hdf2mergedcbf' (head masters) 1 1
>       In a case alternative:
>           (SomeDataCollection SCollect SHdf5 _)
>             -> hdf2mergedcbf' (head masters) 1 1
>       In the second argument of ‘($)’, namely
>         ‘case col of
>            (SomeDataCollection SCollect SHdf5 _)
>              -> hdf2mergedcbf' (head masters) 1 1
>            (SomeDataCollection SCollect SHdf5' _) -> undefined
>            (SomeDataCollection SCaracterization SHdf5 _) -> undefined
>            (SomeDataCollection SCaracterization SHdf5' _) -> undefined
>            _ -> error "show not arrive here !!!"’
>     |
> 180 |         (SomeDataCollection SCollect SHdf5 _)          ->
> hdf2mergedcbf' (head masters) 1 1
>     |
>  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>
> What I do not understand is how to fix this since it seems that
>
>   liftIO $ hdf2mergedcbf' (head masters) 1 1  works out of the case
>
> thanks for your help
>
> Frederic
>
> ------------------------------
>
> Message: 4
> Date: Fri, 29 Nov 2019 12:29:23 +0100
> From: Sylvain Henry <sylvain at haskus.fr>
> To: <beginners at haskell.org>
> Subject: Re: [Haskell-beginners] strange error inside a case
> Message-ID: <7c062774-ff78-569a-fba5-543eccf7cecd at haskus.fr>
> Content-Type: text/plain; charset="utf-8"; format=flowed
>
> Hello,
>
> What is the type of hdf2mergedcbf' ?
>
> Does it work if you write `void (hdf2mergedcbf' (head masters) 1 1)` ?
>
>
> On 29/11/2019 11:55, PICCA Frederic-Emmanuel wrote:
> > Hello, I aheve some code whcih look like this
> >
> > thumbnail' :: (MonadIO m, MonadReader Beamline m, MonadThrow m) =>
> ThumbnailInput -> m ()
> > thumbnail' (ThumbnailInput col) = do
> >    cwd <- toResultsPath "thumbnail" col
> >    let shakeFiles' =  cwd </> $(mkRelDir ".shake/")
> >    let shakeReport' = shakeFiles' </> $(mkRelFile "report.html")
> >
> >    liftIO $ shake shakeOptions{ shakeFiles=fromAbsDir shakeFiles'
> >                               , shakeReport=[fromAbsFile shakeReport']
> >                               , shakeVerbosity=Diagnostic
> >                               } $ do
> >      let uploaded = fromAbsFile $ cwd </> $(mkRelFile
> "thumbnail.uploaded")
> >
> >      want [uploaded]
> >
> >      -- (Rule 1) merge the image files
> >      uploaded %> \_out -> do
> >        -- need [xml]
> >        masters <- liftIO $ expectedInputFiles col
> >        liftIO $ hdf2mergedcbf' (head masters) 1 1
> >        liftIO $ case col of
> >          (SomeDataCollection SCollect SHdf5 _)          ->
> hdf2mergedcbf' (head masters) 1 1
> >          (SomeDataCollection SCollect SHdf5' _)         -> undefined --
> hdf2mergedcbf' (head masters) 1 1
> >          (SomeDataCollection SCaracterization SHdf5 _)  -> undefined
> >          (SomeDataCollection SCaracterization SHdf5' _) -> undefined
> >          _                                              -> error "show
> not arrive here !!!"
> >
> >        -- hdf2mergedcbf
> >        -- command [] "touch" [uploaded]
> >        return ()
> >
> >
> > When I try to compile it, it give me this error
> >
> >      • Couldn't match type ‘a0’ with ‘()’
> >          ‘a0’ is untouchable
> >            inside the constraints: f ~ 'ISPyB.DataCollection.Hdf5
> >            bound by a pattern with constructor:
> >                       SHdf5 :: SCollectSourceFormat
> 'ISPyB.DataCollection.Hdf5,
> >                     in a case alternative
> >            at src/Thumbnail.hs:180:38-42
> >        Expected type: IO a0
> >          Actual type: IO ()
> >      • In the expression: hdf2mergedcbf' (head masters) 1 1
> >        In a case alternative:
> >            (SomeDataCollection SCollect SHdf5 _)
> >              -> hdf2mergedcbf' (head masters) 1 1
> >        In the second argument of ‘($)’, namely
> >          ‘case col of
> >             (SomeDataCollection SCollect SHdf5 _)
> >               -> hdf2mergedcbf' (head masters) 1 1
> >             (SomeDataCollection SCollect SHdf5' _) -> undefined
> >             (SomeDataCollection SCaracterization SHdf5 _) -> undefined
> >             (SomeDataCollection SCaracterization SHdf5' _) -> undefined
> >             _ -> error "show not arrive here !!!"’
> >      |
> > 180 |         (SomeDataCollection SCollect SHdf5 _)          ->
> hdf2mergedcbf' (head masters) 1 1
> >      |
>  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> >
> >
> > What I do not understand is how to fix this since it seems that
> >
> >    liftIO $ hdf2mergedcbf' (head masters) 1 1  works out of the case
> >
> > thanks for your help
> >
> > Frederic
> > _______________________________________________
> > Beginners mailing list
> > Beginners at haskell.org
> > http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
>
> ------------------------------
>
> Subject: Digest Footer
>
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
>
> ------------------------------
>
> End of Beginners Digest, Vol 137, Issue 13
> ******************************************
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20191129/7a91214c/attachment-0001.html>

From frederic-emmanuel.picca at synchrotron-soleil.fr  Fri Nov 29 18:23:45 2019
From: frederic-emmanuel.picca at synchrotron-soleil.fr (PICCA Frederic-Emmanuel)
Date: Fri, 29 Nov 2019 18:23:45 +0000
Subject: [Haskell-beginners] strange error inside a case
In-Reply-To: <7c062774-ff78-569a-fba5-543eccf7cecd@haskus.fr>
References: <A2A20EC3B8560D408356CAC2FC148E53017D83AB1A@SUN-DAG3.synchrotron-soleil.fr>,
 <7c062774-ff78-569a-fba5-543eccf7cecd@haskus.fr>
Message-ID: <A2A20EC3B8560D408356CAC2FC148E53017D83ACB5@SUN-DAG3.synchrotron-soleil.fr>

> What is the type of hdf2mergedcbf' ?

hdf2mergedcbf' :: Path Abs File -> Int -> Int -> IO ()

> Does it work if you write `void (hdf2mergedcbf' (head masters) 1 1)` ?

nop

    • In the expression: void (hdf2mergedcbf' (head masters) 1 1)
      In a case alternative:
          (SomeDataCollection SCollect SHdf5 _)
            -> void (hdf2mergedcbf' (head masters) 1 1)
      In the second argument of ‘($)’, namely
        ‘case col of {
           (SomeDataCollection SCollect SHdf5 _)
             -> void (hdf2mergedcbf' (head masters) 1 1) }’
    |
184 |         (SomeDataCollection SCollect SHdf5 _)          -> void (hdf2mergedcbf' (head masters) 1 1)
    |                                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

HsCompilation exited abnormally with code 1 at Fri Nov 29 19:23:04