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2020-10-28 22:17:32 <jle`> i thiiink it should be possible actually
2020-10-28 22:17:32 <koz_> I mean, yeah. Your starting value is the mempty.
2020-10-28 22:17:38 <jle`> just use foldM to get [m a]
2020-10-28 22:17:42 <jle`> and foldMapA id
2020-10-28 22:17:45 <koz_> Lol.
2020-10-28 22:17:47 <koz_> Ah yes.
2020-10-28 22:17:51 <koz_> 'Hack everythign into list'.
2020-10-28 22:18:00 <koz_> Aka 'how all of Foldable works'.
2020-10-28 22:18:50 <koz_> Although realistically, by its very nature, 'toList' falls out of Traversable even if Foldable weren't a thing.
2020-10-28 22:19:29 <koz_> (or heck, toX, where X is some linear collection with concatenation and emptiness as concepts)
2020-10-28 22:19:45 <koz_> (or heck, it doesn't even technically have to be a _linear_ collection)
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2020-10-28 22:24:18 <jle`> yeah, Foldable is baby Traversable :)
2020-10-28 22:25:16 <koz_> And basically, we get 'emptiness and concatenation' as a special case of Monoid.
2020-10-28 22:25:29 <koz_> Basically, it really is all traverse and monoids all the way down.
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2020-10-28 23:17:10 <crestfallen> Hi .. I understand most of this paste. it clarifies that (->) is not a morphism (I guess a morphism cannot be binary?) ; and that fmap for Functor (-> r) is composition. So generally fmap is a morphism, perhaps the most basic one? https://termbin.com/evcw
2020-10-28 23:17:43 Kaiepi joins (~Kaiepi@nwcsnbsc03w-47-55-225-82.dhcp-dynamic.fibreop.nb.bellaliant.net)
2020-10-28 23:18:40 <crestfallen> I see how the expansion of (->) r (fmap) is composition.
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2020-10-28 23:21:35 <crestfallen> so my question is, if the above is correct, are there morphisms more simple than fmap?
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2020-10-28 23:22:10 <bsima> how do i convert a Decimal to a Float or Int?
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2020-10-28 23:22:33 <Axman6> what's a Decimal?
2020-10-28 23:22:36 ulidtko|k joins (~ulidtko@193.111.48.79)
2020-10-28 23:22:38 <bsima> Data.Decimal
2020-10-28 23:22:39 <ghoulguy> probably: realToFrac and truncate
2020-10-28 23:22:56 nbloomf joins (~nbloomf@2600:1700:ad14:3020:1c75:523e:ddcb:cd98)
2020-10-28 23:23:06 <ghoulguy> truncate or round, depending on which behavior you want
2020-10-28 23:23:39 <Axman6> :t realToFrac
2020-10-28 23:23:40 <lambdabot> (Real a, Fractional b) => a -> b
2020-10-28 23:24:21 <crestfallen> or are there morphisms I've probably come across before?
2020-10-28 23:24:27 <bsima> i think realToFrac is what I wanted, thanks
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2020-10-28 23:25:34 <crestfallen> also I'm trying to see if and how (->) r is partial application
2020-10-28 23:25:58 <crestfallen> a bit confused..
2020-10-28 23:26:41 <Axman6> it's a partial application of the type (->) but doesn't represent partial application of functions to values - ((->) r) is all functions which can accept an r
2020-10-28 23:26:43 <lyxia> crestfallen: I'm not sure what you mean by "morphism"
2020-10-28 23:27:03 <crestfallen> https://termbin.com/evcw lyxia it's the blurb at the top
2020-10-28 23:27:45 <crestfallen> all functions which can accept an r Axman6 ...
2020-10-28 23:27:53 <lyxia> crestfallen: I don't find that paste particularly good, notably because it starts by using the word "morphism" in an unconventional way, if it makes sense at all.
2020-10-28 23:28:23 <crestfallen> really ok. lyxia thanks, what about below the paragraph though?
2020-10-28 23:29:47 falafel joins (~falafel@71-34-132-121.clsp.qwest.net)
2020-10-28 23:30:17 <lyxia> The important part is that ((->) r) is a mapping from types to types, that's the first condition for something to be in the Functor class in Haskell.
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2020-10-28 23:31:15 <lyxia> But it's worth mentioning that the Functor class in Haskell is itself a restriction of amuch more general idea of functors in category theory, where they don't necessarily map types to types.
2020-10-28 23:31:49 mdrjr1 joins (~mdrjr@217.146.82.202)
2020-10-28 23:32:25 <lyxia> So this paragraph is talking in terms of categories about the very restricted notion of Functor in Haskell, that's bound to mix up ideas and confuse people.
2020-10-28 23:32:44 <crestfallen> yeah, i.e. an object doesn't need to be a type. like it can be a group I think lyxia
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2020-10-28 23:36:34 <monsterchrom> Who wrote that?
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2020-10-28 23:36:56 <crestfallen> thanks lyxia and Axman6 monsterchrom one sec
2020-10-28 23:37:33 <lyxia> monsterchrom: did you change your nick
2020-10-28 23:37:41 <monsterchrom> There is a reason in a 1st-year linear algebra course we don't go "use the Yoneda lemma to prove that every elementary row operation is representable by multiplying by a matrix", even though it is totally true.

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