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Today's Topics:
1. newEmptyMVar return type (Velichko Lefterov)
2. Re: newEmptyMVar return type (Velichko Lefterov)
3. Re: newEmptyMVar return type (David McBride)
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Message: 1
Date: Tue, 5 Jan 2021 20:22:50 +0200
From: Velichko Lefterov <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: [Haskell-beginners] newEmptyMVar return type
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Hello,
could someone explain me simple how return-type polymorphism works
in the following case:
newEmptyMVar :: IO (MVar a) ?
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Message: 2
Date: Wed, 6 Jan 2021 08:37:03 +0200
From: Velichko Lefterov <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] newEmptyMVar return type
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OK,
I tried this one:
test:: IO (Maybe a)
test = return Nothing
It looks similar and it seems to work...
On Tue, Jan 5, 2021 at 8:22 PM Velichko Lefterov <
[email protected]> wrote:
> Hello,
> could someone explain me simple how return-type polymorphism works
> in the following case:
> newEmptyMVar :: IO (MVar a) ?
>
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Message: 3
Date: Wed, 6 Jan 2021 06:37:52 -0500
From: David McBride <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] newEmptyMVar return type
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<can+tr41ecoxgwtl4krbkuyvu6nknnt9wfb0zn+i-ydvcn10...@mail.gmail.com>
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It means that the function can return an mvar containing any type that you
need. What type it returns depends on what type your program asks for.
On Wed, Jan 6, 2021, 01:37 Velichko Lefterov <[email protected]>
wrote:
> OK,
> I tried this one:
>
> test:: IO (Maybe a)
> test = return Nothing
>
> It looks similar and it seems to work...
>
> On Tue, Jan 5, 2021 at 8:22 PM Velichko Lefterov <
> [email protected]> wrote:
>
>> Hello,
>> could someone explain me simple how return-type polymorphism works
>> in the following case:
>> newEmptyMVar :: IO (MVar a) ?
>>
> _______________________________________________
> Beginners mailing list
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> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
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