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Today's Topics:
1. Re: Haskell laziness and data structures. (Marcin Mrotek)
2. Re: Haskell laziness and data structures. (OxFord)
3. search function by type (OxFord)
4. Re: search function by type (Andrew Bernard)
----------------------------------------------------------------------
Message: 1
Date: Thu, 7 Jul 2016 19:05:43 +0200
From: Marcin Mrotek <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Haskell laziness and data structures.
Message-ID:
<cajcfpzkvkgghsondshxnpgwjb2j3p3x0f2m+jk1merttbcu...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Hello,
> Why is there no default O(1) random access list data structure in haskell
> (for example clojure has [] vector). I would expect that this kind of data
> structure is used very often, so you shouldn't need to import one yourself.
Vector (https://hackage.haskell.org/package/vector) can be considered
standard for all intents and purposes; it's one of the core libraries
(https://wiki.haskell.org/Library_submissions#The_Libraries).
Containers in Haskell are in general imported as libraries, it's no
different than Map, Set, or Sequence, for example. I'm not sure if
it's used all that often in Haskell - it's excellent for numeric code,
or other cases when one just needs a big dumb block of data (though
streaming with pipes or conduit might be a better solution in some
cases), but for otherwise something like IntMap or Sequence might be
more useful.
>Why is array indexeded by ! and list by !!. Shouldn't they be both instances
>of something like Indexable?
Indexing a list is O(n) and generally a bad idea. Proliferating type
classes just to cover the rare use case of code that is indifferent to
whether the indexing is done in O(n) or O(1) seems pointless to me.
Best regards,
Marcin Mrotek
------------------------------
Message: 2
Date: Thu, 7 Jul 2016 19:16:44 +0200
From: OxFord <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] Haskell laziness and data structures.
Message-ID:
<capq-+hkdfy11eqq7xxo-r-rgah85l8-plasaos--sdkckgy...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Thanks !
2016-07-07 19:05 GMT+02:00 Marcin Mrotek <[email protected]>:
> Hello,
>
> > Why is there no default O(1) random access list data structure in haskell
> > (for example clojure has [] vector). I would expect that this kind of
> data
> > structure is used very often, so you shouldn't need to import one
> yourself.
>
> Vector (https://hackage.haskell.org/package/vector) can be considered
> standard for all intents and purposes; it's one of the core libraries
> (https://wiki.haskell.org/Library_submissions#The_Libraries).
> Containers in Haskell are in general imported as libraries, it's no
> different than Map, Set, or Sequence, for example. I'm not sure if
> it's used all that often in Haskell - it's excellent for numeric code,
> or other cases when one just needs a big dumb block of data (though
> streaming with pipes or conduit might be a better solution in some
> cases), but for otherwise something like IntMap or Sequence might be
> more useful.
>
> >Why is array indexeded by ! and list by !!. Shouldn't they be both
> instances of something like Indexable?
>
> Indexing a list is O(n) and generally a bad idea. Proliferating type
> classes just to cover the rare use case of code that is indifferent to
> whether the indexing is done in O(n) or O(1) seems pointless to me.
>
> Best regards,
> Marcin Mrotek
> _______________________________________________
> Beginners mailing list
> [email protected]
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
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Message: 3
Date: Thu, 7 Jul 2016 19:30:44 +0200
From: OxFord <[email protected]>
To: "[email protected]" <[email protected]>
Subject: [Haskell-beginners] search function by type
Message-ID:
<CAPQ-+HLdpH2chgAwqMuj6umd4=8u886jyfa2H1TU=njue6c...@mail.gmail.com>
Content-Type: text/plain; charset="utf-8"
Hello,
is it possible to search for all functions that have concrete type?
For example I want to convert [Char] to [Word], but I don't know whether
function for that exist.
Or I wanna find contructor for SomeSpecialType and I don't know it's name.
Can you search those function in GHCI via some command?
E.G.
GHCi, version 8.0.1: http://www.haskell.org/ghc/ :? for help
[}{] :searchtype / :st [Char] -> [Word]
Found X match(es):
foo1 :: (Char -> Word) -> [Char] -> [Word]
foo2 :: [Char] -> [Word]
...
[}{] :st SomeSpecialType
Found 1 match(es):
foo3 :: ... -> .. -> SomeSpecialType
King Regards,
Ford
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Message: 4
Date: Fri, 8 Jul 2016 17:37:22 +1000
From: Andrew Bernard <[email protected]>
To: The Haskell-Beginners Mailing List - Discussion of primarily
beginner-level topics related to Haskell <[email protected]>
Subject: Re: [Haskell-beginners] search function by type
Message-ID:
<CAK5QfnWPJA7S=ajv+tpjkuz667npjxppwzmvw6sixbj2h8c...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Hi Ford,
Take a look at Hoogle. Indispensable.
https://www.haskell.org/hoogle/
Andrew
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