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Today's Topics:
1. The (x:xs) in function parameter is a tuple? (Nan Xiao)
2. Re: The (x:xs) in function parameter is a tuple?
(Sumit Sahrawat, Maths & Computing, IIT (BHU))
3. Re: The (x:xs) in function parameter is a tuple?
(Imants Cekusins)
----------------------------------------------------------------------
Message: 1
Date: Wed, 24 Feb 2016 18:31:49 +0800
From: Nan Xiao <[email protected]>
To: [email protected]
Subject: [Haskell-beginners] The (x:xs) in function parameter is a
tuple?
Message-ID:
<ca+mhoambg6d+d2vvrjptnjabhmn4zqerwdetkdhkkpow3oe...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Hi all,
Greetings from me!
I am confused about the function parameters and tuple. E.g.:
occurs value [] = 0
occurs value (x:xs) = (if value == x then 1 else 0) + occurs value xs
should we consider (x:xs) as a tuple?
Thanks in advance!
Best Regards
Nan Xiao
------------------------------
Message: 2
Date: Wed, 24 Feb 2016 16:14:04 +0530
From: "Sumit Sahrawat, Maths & Computing, IIT (BHU)"
<[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] The (x:xs) in function parameter is a
tuple?
Message-ID:
<cajbew8mi5tsvnzsduvhhn13gawg_myghwsinsbfexvquvod...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
(:) is a constructor. For example, you can define lists as:
data List a = Nil | Cons a (List a)
GHC does some magic to provide us with the same definition, but with Nil
replaced by [] and Cons replaced by (:).
As constructors can be pattern matched on, you can also match on a (:),
which is a data constructor.
You might consider (x:xs) as a tuple, only if you're willing to consider
(Cons x xs) as a tuple. It is a tuple (ordered collection of two values),
but not a tuple according to their definition in haskell.
What kind of tuple are you talking about?
Hope this helps.
Regards,
Sumit
On 24 February 2016 at 16:01, Nan Xiao <[email protected]> wrote:
> Hi all,
>
> Greetings from me!
>
> I am confused about the function parameters and tuple. E.g.:
>
> occurs value [] = 0
> occurs value (x:xs) = (if value == x then 1 else 0) + occurs value xs
>
> should we consider (x:xs) as a tuple?
>
> Thanks in advance!
>
> Best Regards
> Nan Xiao
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
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Message: 3
Date: Wed, 24 Feb 2016 11:45:23 +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] The (x:xs) in function parameter is a
tuple?
Message-ID:
<CAP1qinbkeGCCFdDFObtoLWrVHbOPX6t4TKeDYvnZ+mPVZyW=x...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Hello Xiao,
(one_element) -- is evaluation
(element,element,...) -- is tuple
(1:[2]) -- [1,2] because it is one "array element"
(1,2) -- is a tuple because there are 2 elements
------------------------------
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