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Today's Topics:
1. Re: How to avoid repeating a type restriction from a
data
constructor (Daniel Fischer)
2. Haskell training in San Francisco Bay Area and New York
(Duncan Coutts)
3. two System.IO.Strict modules (Hong Yang)
----------------------------------------------------------------------
Message: 1
Date: Thu, 25 Apr 2013 12:06:36 +0200
From: Daniel Fischer <[email protected]>
Subject: Re: [Haskell-beginners] How to avoid repeating a type
restriction from a data constructor
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset="us-ascii"
On Thursday 25 April 2013, 08:03:25, gs wrote:
> Daniel Fischer <daniel.is.fischer <at> googlemail.com> writes:
> > ...
>
> You've mentioned GADT a few times, but I can't find a case where it's
> different to regular datatypes.
>
> data Foo a = Eq a => Foo a
>
> seems to have the same effect as
>
> data Foo a where
> Foo a :: Eq a => a -> Foo a
>
> Both remember the Eq constraint if I pattern match on the constructor, and
> both ignore it otherwise.
Oy, sorry, I didn't look properly and moved the constraint before the datatype
name (data Eq a => Foo a = Foo a) in my brain, which would be a datatype
context.
The data Foo a = Eq a => Foo a syntax (requires ExistentialQuantification or
GADTs) is indeed equivalent to the GADT syntax or existential quantification.
Oh well, at least the part explaining how that requires pattern matching to
make the context available remains useful.
------------------------------
Message: 2
Date: Thu, 25 Apr 2013 15:50:18 +0100
From: Duncan Coutts <[email protected]>
Subject: [Haskell-beginners] Haskell training in San Francisco Bay
Area and New York
To: [email protected]
Message-ID: <[email protected]>
Content-Type: text/plain; charset="UTF-8"
Well-Typed are offering Haskell courses in the San Francisco Bay Area
and New York in early June.
They are for professional developers who want to learn Haskell or
improve their skills. There is a 2-day introductory course and a 2-day
advanced course.
Full course and registration details:
http://www.well-typed.com/services_training
Well-Typed are running these courses in partnership with FP Complete and
Skills Matter.
Locations, dates
================
San Francisco Bay Area
* Introductory Course: June 4-5th, 2013
* Advanced Course: June 6-7th, 2013
New York
* Introductory Course: June 10-11th, 2013
* Advanced Course: June 12-13th, 2013
* Early bird discount before April 29th
--
Duncan Coutts, Haskell Consultant
Well-Typed LLP, http://www.well-typed.com/
------------------------------
Message: 3
Date: Thu, 25 Apr 2013 22:12:45 -0500
From: Hong Yang <[email protected]>
Subject: [Haskell-beginners] two System.IO.Strict modules
To: [email protected]
Message-ID:
<CA+_A4U6K5==ed9dvbxmulwh0njcdxt8y6r1g1frfwfhfmpm...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
There are two modules called the same name: System.IO.Strict, documented
respectively at
http://hackage.haskell.org/packages/archive/strict-io/0.2.1/doc/html/System-IO-Strict.html
http://hackage.haskell.org/package/strict-0.3.2
My questions are:
1) Will these two modules coexist in the same version of GHC? Or put it
another way, both modules' .tar.gz files have System/IO/Strict.hs inside,
will they overlap in physical disk? From where can I tell which locations
they will be installed to?
2) If yes, which module will "import System.IO.Strict" actually use?
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