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Today's Topics:
1. wxHaskell: add an external event from another thread (Puck)
2. Pattern Matching for record syntax (Jeon-Young Kang)
3. Re: Pattern Matching for record syntax (Magnus Therning)
4. Re: Pattern Matching for record syntax (Imants Cekusins)
5. Re: Pattern Matching for record syntax (Jeon-Young Kang)
6. Re: Pattern Matching for record syntax (Imants Cekusins)
7. Re: Pattern Matching for record syntax (Imants Cekusins)
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Message: 1
Date: Thu, 7 Jan 2016 22:27:44 +0100
From: Puck <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [Haskell-beginners] wxHaskell: add an external event from
another thread
Message-ID: <20160107222744.283494eb@noordzee>
Content-Type: text/plain; charset=US-ASCII
Hello all,
how is it possible to process external events, for example a
succeeded getLine or a takeMVar with its values in the wxHaskell
framework?
The reason is, that I want to connect a erlang node to wxHaskell.
I have found the functions
Graphics.UI.WX.Events.newEvent :: String -> (w -> IO a) -> (w -> a ->
IO ()) -> Event w a
"Create a new event from a get and set function."
Beside from, that I don't know what the get and set function shall do, I
don't know, how I can add the new event to the event-loop of wx, and
when it "fires".
Do you know any possibilities?
Thank you in advance
------------------------------
Message: 2
Date: Thu, 7 Jan 2016 16:54:47 -0500
From: Jeon-Young Kang <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>,
[email protected]
Subject: [Haskell-beginners] Pattern Matching for record syntax
Message-ID:
<CALWtiK8_+Hh_ZVM-J_RgKHRY=cykfhy4cb9zph+c7bqfu9f...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Dear All.
Hope your 2016 is off to a great start.
I would like to get results from pattern matching or something.
Here is the my code.
data Person = Person {name :: String, age :: Int}
names = ["tom", "sara"] -- list of names, String
persons = [Person {name = "tom", age = 10}, Person {name="sara", age=9},
Person {name = "susan", age = 8}].
Is there any solution to get the age of "tom" and "sara"?
I have no idea of pattern matching for this one.
I've tried to use recursion, but I couldn't find any solution for list of
records.
Sincerely,
Young
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Message: 3
Date: Thu, 07 Jan 2016 23:24:18 +0100
From: Magnus Therning <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Cc: [email protected]
Subject: Re: [Haskell-beginners] Pattern Matching for record syntax
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
Jeon-Young Kang writes:
> Dear All.
>
> Hope your 2016 is off to a great start.
>
> I would like to get results from pattern matching or something.
>
> Here is the my code.
>
> data Person = Person {name :: String, age :: Int}
>
> names = ["tom", "sara"] -- list of names, String
>
> persons = [Person {name = "tom", age = 10}, Person {name="sara", age=9},
> Person {name = "susan", age = 8}].
>
> Is there any solution to get the age of "tom" and "sara"?
>
> I have no idea of pattern matching for this one.
>
> I've tried to use recursion, but I couldn't find any solution for list of
> records.
How about using `filter`[1] over `persons` with a function checking if
the name is in `names`?
I'm sorry, but this sounds like home work so you won't get more than
this from me.
/M
[1]:
http://hackage.haskell.org/package/base-4.8.1.0/docs/Data-List.html#v:filter
--
Magnus Therning OpenPGP: 0x927912051716CE39
email: [email protected] jabber: [email protected]
twitter: magthe http://therning.org/magnus
Would you go to war without a helmet? Would you drive without the seat
belt? Then why do you develop software as if shit doesn?t happen?
-- Alberto G ( http://makinggoodsoftware.com/2009/05/12/hdd/ )
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Message: 4
Date: Thu, 7 Jan 2016 23:28:54 +0100
From: Imants Cekusins <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Pattern Matching for record syntax
Message-ID:
<CAP1qinbze4Gf+L_uPz0O-J=nmufhm-xv8mkqzm1s-msq97q...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
you could filter record list
http://hackage.haskell.org/package/base-4.8.1.0/docs/Prelude.html#v:filter
\r -> elem (name r) names
then fmap the filtered list to extract age
age <$> list1
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Message: 5
Date: Thu, 7 Jan 2016 17:29:10 -0500
From: Jeon-Young Kang <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Pattern Matching for record syntax
Message-ID:
<calwtik-vrfcbmzqc553fc-yt+p3p2_fdo5th1i291_4jkwk...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Thanks Magnus Therning.
Actually, this is NOT homework. I am just studying Haskell for my current
research.
I've tried "filter" before. But I couldn't reach what I want to do.
it seems that filter is only applicable to list, not "record syntax".
Do I need functor for this??
Best,
On Thu, Jan 7, 2016 at 5:24 PM, Magnus Therning <[email protected]> wrote:
>
> Jeon-Young Kang writes:
>
> > Dear All.
> >
> > Hope your 2016 is off to a great start.
> >
> > I would like to get results from pattern matching or something.
> >
> > Here is the my code.
> >
> > data Person = Person {name :: String, age :: Int}
> >
> > names = ["tom", "sara"] -- list of names, String
> >
> > persons = [Person {name = "tom", age = 10}, Person {name="sara", age=9},
> > Person {name = "susan", age = 8}].
> >
> > Is there any solution to get the age of "tom" and "sara"?
> >
> > I have no idea of pattern matching for this one.
> >
> > I've tried to use recursion, but I couldn't find any solution for list of
> > records.
>
> How about using `filter`[1] over `persons` with a function checking if
> the name is in `names`?
>
> I'm sorry, but this sounds like home work so you won't get more than
> this from me.
>
> /M
>
> [1]:
> http://hackage.haskell.org/package/base-4.8.1.0/docs/Data-List.html#v:filter
>
> --
> Magnus Therning OpenPGP: 0x927912051716CE39
> email: [email protected] jabber: [email protected]
> twitter: magthe http://therning.org/magnus
>
> Would you go to war without a helmet? Would you drive without the seat
> belt? Then why do you develop software as if shit doesn?t happen?
> -- Alberto G ( http://makinggoodsoftware.com/2009/05/12/hdd/ )
>
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
>
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Message: 6
Date: Thu, 7 Jan 2016 23:33:55 +0100
From: Imants Cekusins <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Pattern Matching for record syntax
Message-ID:
<CAP1qinbqTYMUoSHXb0cEhvceGu=ssrwkqdhvqddeb8hj-bg...@mail.gmail.com>
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if you must use pattern matching, here is a tip:
(Person name0 age0)
i.e. records are like tuples with values in the order of declared record
fields.
name0 can be named anything else. To match any field value, use _ for that
field
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Message: 7
Date: Thu, 7 Jan 2016 23:37:44 +0100
From: Imants Cekusins <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Pattern Matching for record syntax
Message-ID:
<CAP1qinbAHU5NUTcf8Z9AsGEb16d+CKQUD2fUJrp9yfM-NM=a...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
> filter is only applicable to list, not "record syntax".
but [Person] is the input, isn't it?
> Do I need functor for this??
no need to define new functor instance to filter over a list of records.
but you could use fmap over list, yes
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