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2020-09-27 14:28:22 → josh_ joins (~josh@c-67-164-104-206.hsd1.ca.comcast.net)
2020-09-27 14:31:49 → Chefe joins (~Chefe@84.39.117.57)
2020-09-27 14:34:07 → Guest_67 joins (5284e9b3@82-132-233-179.dab.02.net)
2020-09-27 14:34:44 <Guest_67> .
2020-09-27 14:35:51 <Guest_67> Permission was denied when I wanted to add the required PATH variable to /Users/b/.bashrc
2020-09-27 14:36:59 ← Guest_67 parts (5284e9b3@82-132-233-179.dab.02.net) ()
2020-09-27 14:37:32 <[exa]> p0a: I didn't try to compile this but it might show how to really exploit the list machinery https://paste.tomsmeding.com/crh9oaVX
2020-09-27 14:37:42 → coot joins (~coot@37.30.52.6.nat.umts.dynamic.t-mobile.pl)
2020-09-27 14:38:28 <[exa]> (oh and you might need to place `head $` before `do` to get a single possibility there)
2020-09-27 14:38:41 <p0a> [exa]: that' svery nice
2020-09-27 14:38:50 <p0a> I see you're using guard and also some tricks with *>
2020-09-27 14:38:54 <p0a> I'll have to think about it
2020-09-27 14:39:39 <[exa]> p0a: the monad binding (<-) for lists works like list comprehension, it tries the rest of the code for all values in the list you bound
2020-09-27 14:39:51 → thir joins (~thir@p200300f27f0fc60094e773283d7bf825.dip0.t-ipconnect.de)
2020-09-27 14:40:15 <[exa]> and `guard` kindof terminates the attempt to reach a result if the condition is false
2020-09-27 14:41:24 <[exa]> intuition for the rest: <|> is an "or" for this kind of wrapped computations (if the first branch fails, you still get some results for the second)
2020-09-27 14:41:38 <p0a> right
2020-09-27 14:41:48 <p0a> I'm going to learn from that example
2020-09-27 14:41:55 <[exa]> and *> is a fancy version of "if nothing broke yet, return the thing on the right"
2020-09-27 14:42:03 <p0a> guard seems handy, it's just foreign to me
2020-09-27 14:42:07 → heatsink joins (~heatsink@107-136-5-69.lightspeed.sntcca.sbcglobal.net)
2020-09-27 14:42:17 <p0a> I don't use it because I think I've never seen it before
2020-09-27 14:42:32 <[exa]> I might have simplified that with $> 1 and $> -1 from Data.Functor
2020-09-27 14:42:34 <p0a> (Except for the tutorials/books on haskell that I've read)
2020-09-27 14:42:49 → elliott__ joins (~elliott@pool-100-36-54-163.washdc.fios.verizon.net)
2020-09-27 14:42:54 <[exa]> uh, and list functor/applicative primer:
2020-09-27 14:43:09 <[exa]> > [(+1),(*10)] <*> [1,2,3]
2020-09-27 14:43:11 <lambdabot> [2,3,4,10,20,30]
2020-09-27 14:43:25 <p0a> that reminds me
2020-09-27 14:43:31 <p0a> Why does it work in that fashion?
2020-09-27 14:43:45 <p0a> I saw an example `liftA2 (,) list1 list2' for cartesian product
2020-09-27 14:43:54 <[exa]> > [1,2] $> 10
2020-09-27 14:43:56 <lambdabot> error:
2020-09-27 14:43:56 <lambdabot> • Variable not in scope: ($>) :: [a0] -> t0 -> t
2020-09-27 14:43:56 <lambdabot> • Perhaps you meant one of these:
2020-09-27 14:44:04 <[exa]> oh noes, $> is from Data.Functor
2020-09-27 14:44:07 × thir quits (~thir@p200300f27f0fc60094e773283d7bf825.dip0.t-ipconnect.de) (Ping timeout: 240 seconds)
2020-09-27 14:44:37 <[exa]> p0a: list Applicative instance is derived exactly like that. The semantics is something like "Listing of all possibilities" (with some rough corners about infinities)
2020-09-27 14:45:39 <p0a> why couldn't it be zip-like instead?
2020-09-27 14:45:59 <[exa]> p0a: btw the liftA2 rewrites to the "operator" form like this, I find it kindof more illustrative:
2020-09-27 14:46:00 <p0a> i.e. [(+1),(*10)] <*> [1,2,3] would give [2, 20]
2020-09-27 14:46:16 <[exa]> > (,) <$> [1,2,3] <*> [1,2,3]
2020-09-27 14:46:19 <lambdabot> [(1,1),(1,2),(1,3),(2,1),(2,2),(2,3),(3,1),(3,2),(3,3)]
2020-09-27 14:46:36 <p0a> yeah I see what that means
2020-09-27 14:46:51 × heatsink quits (~heatsink@107-136-5-69.lightspeed.sntcca.sbcglobal.net) (Ping timeout: 258 seconds)
2020-09-27 14:47:11 <p0a> the magic is in <*> then; that's why I'm asking my question above about an alternative definition
2020-09-27 14:47:14 <p0a> would it violate some 'axiom' ?
2020-09-27 14:47:21 <[exa]> p0a: good question; the simple answer is that list comprehension wouldn't work, but I believe there's some slightly more rigorous reason
2020-09-27 14:47:23 <kosmikus> it could be zip-like. in fact, there's a newtype called ZipList that implements exactly that applicative instance. the "default" instance is chosen to be compatible with the monad instance for lists.
2020-09-27 14:48:06 <p0a> oh nice. I see, thank you
2020-09-27 14:49:12 × ericsagnes quits (~ericsagne@2405:6580:0:5100:74e9:5ac6:5b4b:6ddf) (Ping timeout: 260 seconds)
2020-09-27 14:49:57 <[exa]> oh yes there's no (reasonable) way to "flatten" lists by zipping, so their monad instance would have to be kinda fishy (thanks kosmikus!)
2020-09-27 14:50:06 → mirrorbird joins (~psutcliff@h85-8-41-6.cust.a3fiber.se)
2020-09-27 14:51:49 × merijn quits (~merijn@83-160-49-249.ip.xs4all.nl) (Ping timeout: 264 seconds)
2020-09-27 14:52:16 → heatsink joins (~heatsink@107-136-5-69.lightspeed.sntcca.sbcglobal.net)
2020-09-27 14:53:11 → antaoiseach joins (~z0ltan@103.5.134.18)
2020-09-27 14:53:40 → cosimone joins (~cosimone@2001:b07:ae5:db26:b248:7aff:feea:34b6)
2020-09-27 14:54:19 <antaoiseach> Hello folks, I'm just learning about the various GHC extensions, and I was trying this example - https://limperg.de/ghc-extensions/#bangpatterns, but the code does not seem to be working as expected for me.
2020-09-27 14:54:29 <antaoiseach> The code snippet is here https://paste.ofcode.org/AFpzbG8CCY3fftWuYKHuWs
2020-09-27 14:54:48 <[exa]> p0a: btw in case of lists, the `a <- b ; c ....` is basically a fun syntax for `concatMap (\a -> c ...) b`
2020-09-27 14:55:21 <antaoiseach> The linked guide says that with the bang pattern, `main` should execute almost instantly, but that does not seem to be the case when I try it (both in GHCi and GHC).. can anyone help me understand this?
2020-09-27 14:56:20 <[exa]> antaoiseach: are you sure that this amount of recursion should finish almost instantly?
2020-09-27 14:56:49 × heatsink quits (~heatsink@107-136-5-69.lightspeed.sntcca.sbcglobal.net) (Ping timeout: 258 seconds)
2020-09-27 14:56:54 <antaoiseach> exarkun: No, I'm not sure... the guide says that it should - hence my confusion!
2020-09-27 14:57:07 <[exa]> uh, if you _remove_ the ! it can finish instantly because it doesn't have to compute the fibs
2020-09-27 14:57:28 <yushyin> 'Without the bang pattern, the programme terminates almost instantly ...' -- from your source
2020-09-27 14:57:36 <antaoiseach> Oh
2020-09-27 14:57:39 → alx741_ joins (~alx741@186.178.110.72)
2020-09-27 14:57:44 <antaoiseach> Okay ... sorry ... my mistake then! :(
2020-09-27 14:57:52 <[exa]> no problem :]
2020-09-27 14:57:59 <antaoiseach> Hahaha ... sorry guys! :D
2020-09-27 14:58:17 <[exa]> I was myself expecting a completely different kind of twist :D
2020-09-27 14:58:23 <antaoiseach> hahaha! :D
2020-09-27 14:58:58 hackage vulkan 3.6.7 - Bindings to the Vulkan graphics API. https://hackage.haskell.org/package/vulkan-3.6.7 (jophish)
2020-09-27 14:59:08 → kelsey joins (~keteskyl@2600:6c64:7b7f:fa42:2cda:1ff8:55be:a617)
2020-09-27 14:59:23 <antaoiseach> Okay, so maybe I could make better use of this chance and ask a better question then! So I'm done with "Programming in Haskell" (2nd Edition), and loved the book. Now I'm trying to get more into the practical side of things - monad transformers, stack, various extensions etc.
2020-09-27 14:59:31 kelsey is now known as Guest18832
2020-09-27 14:59:33 <antaoiseach> What would you recommend in addition/instead of this path?
2020-09-27 14:59:48 Guest18832 is now known as keteskyl
2020-09-27 14:59:55 <antaoiseach> To move from a basic but relatively strong theoretical foundation onto more advanced and practical stuff?
2020-09-27 15:00:02 × Chefe quits (~Chefe@84.39.117.57) ()
2020-09-27 15:00:39 → Lord_of_Life_ joins (~Lord@unaffiliated/lord-of-life/x-0885362)
2020-09-27 15:01:39 → ericsagnes joins (~ericsagne@2405:6580:0:5100:652c:34a0:8a11:d7f2)
2020-09-27 15:01:58 <maralorn> Can I newtype derive an instance for "MyClass MyType B" when there is an instance "MyClass A B" and a "newtype MyType = MyType A"?
2020-09-27 15:02:11 × Lord_of_Life quits (~Lord@unaffiliated/lord-of-life/x-0885362) (Ping timeout: 258 seconds)
2020-09-27 15:02:26 → heatsink joins (~heatsink@107-136-5-69.lightspeed.sntcca.sbcglobal.net)
2020-09-27 15:02:31 <maralorn> antaoiseach: I like http://dev.stephendiehl.com/hask/
2020-09-27 15:02:37 × machinedgod quits (~machinedg@24.105.81.50) (Ping timeout: 264 seconds)
2020-09-27 15:03:16 Lord_of_Life_ is now known as Lord_of_Life
2020-09-27 15:03:37 <antaoiseach> maralorn: Thank you.. that looks very nicely organised indeed!
2020-09-27 15:04:38 <antaoiseach> maralorn: yes, that looks almost exactly like what I am looking for right now. Thanks again! :-)
2020-09-27 15:04:40 → asavan joins (585a3df0@ti0059a400-5844.bb.online.no)
2020-09-27 15:05:40 × antaoiseach quits (~z0ltan@103.5.134.18) (Quit: leaving)
2020-09-27 15:05:51 × coot quits (~coot@37.30.52.6.nat.umts.dynamic.t-mobile.pl) (Quit: coot)
2020-09-27 15:07:18 × heatsink quits (~heatsink@107-136-5-69.lightspeed.sntcca.sbcglobal.net) (Ping timeout: 260 seconds)
2020-09-27 15:09:01 → jneira[m] joins (~jneira@125.red-193-152-119.dynamicip.rima-tde.net)
2020-09-27 15:10:08 × keteskyl quits (~keteskyl@2600:6c64:7b7f:fa42:2cda:1ff8:55be:a617) (Quit: WeeChat 2.8)
2020-09-27 15:12:40 → heatsink joins (~heatsink@107-136-5-69.lightspeed.sntcca.sbcglobal.net)
2020-09-27 15:14:40 → oisdk joins (~oisdk@2001:bb6:3329:d100:b45e:e1cb:af9:6e8)
2020-09-27 15:15:32 × zaquest quits (~notzaques@5.128.210.178) (Quit: Leaving)
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