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2020-09-24 13:37:06 × ystael quits (~ystael@209.6.50.55) (Quit: Lost terminal)
2020-09-24 13:37:24 <Xnuk> bye
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2020-09-24 13:51:02 × Saukk quits (~Saukk@2001:998:dc:4a67:1c59:9bb5:b94c:4) (Remote host closed the connection)
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2020-09-24 13:53:08 → shad0w_ joins (~shad0w_@160.202.37.157)
2020-09-24 13:53:19 <shad0w_> hi all.
2020-09-24 13:53:38 <shad0w_> i am currently learning about Functors on my haskell quest
2020-09-24 13:53:57 <shad0w_> as an exercise, i need to write the Functor for the data type
2020-09-24 13:54:01 <shad0w_> `data ITree a = Leaf (Int -> a) | Node [ITree a]`
2020-09-24 13:54:15 → filwisher joins (~filwisher@cpc76738-dals23-2-0-cust186.20-2.cable.virginm.net)
2020-09-24 13:54:46 × darjeeling_ quits (~darjeelin@122.245.123.72) (Ping timeout: 256 seconds)
2020-09-24 13:54:51 <shad0w_> what i came up with was
2020-09-24 13:54:54 <shad0w_> `
2020-09-24 13:54:57 <shad0w_> instance Functor ITree where
2020-09-24 13:54:57 <shad0w_> fmap g (Leaf f) = Leaf (g . f)
2020-09-24 13:54:57 <shad0w_> fmap _ (Node []) = Node []
2020-09-24 13:54:57 <shad0w_> fmap g (Node (x:xs)) = Node ([(fmap g x)] ++ [fmap g (Node xs)])
2020-09-24 13:54:58 <shad0w_> `
2020-09-24 13:54:58 <[exa]> shad0w_: please pastebin :]
2020-09-24 13:55:15 → darjeeling_ joins (~darjeelin@122.245.123.72)
2020-09-24 13:55:25 <shad0w_> alright
2020-09-24 13:55:48 → heatsink joins (~heatsink@107-136-5-69.lightspeed.sntcca.sbcglobal.net)
2020-09-24 13:55:56 <[exa]> anyway when it's already here, it looks pretty much okay, the question is why would you create a new Node for fmapping again if you already have stripped the "wrap" once?
2020-09-24 13:57:01 <[exa]> (hint: recursing manually is sometimes just confusing, if you want to do the same action all over some kind of list, just use `map`)
2020-09-24 13:57:03 <shad0w_> https://paste.ofcode.org/dxSxd9D9zkSqj86AvE6uXF
2020-09-24 13:57:14 → irc_user joins (uid423822@gateway/web/irccloud.com/x-kkhmlwcffthfhnqd)
2020-09-24 13:57:34 <shad0w_> it wouldn't pass the typechecker any other way i tried.
2020-09-24 13:58:02 <shad0w_> this passed the type check but had me a little confused if it does what i think it does
2020-09-24 13:58:07 <[exa]> shad0w_: (about pastebins -- pasting more than ~2-3 lines to IRC is widely frowned upon, people here generally don't mind a lot but pastebinning is safer)
2020-09-24 13:58:13 × Kaivo quits (~Kaivo@104-200-86-99.mc.derytele.com) (Ping timeout: 246 seconds)
2020-09-24 13:58:50 <shad0w_> [exa]: i'll be mindfull of that, thanks. im new here. so my IRC ettiquites are a little (non-existant) lol
2020-09-24 13:59:36 <[exa]> shad0w_: anyway, try giving the compiler this line (instd of both your variants for Node:
2020-09-24 13:59:50 <[exa]> fmap g (Node a) = Node $ map _ a
2020-09-24 14:00:25 <[exa]> the _ should produce a "nice" error that tells you what type you need to smash in there
2020-09-24 14:00:49 × heatsink quits (~heatsink@107-136-5-69.lightspeed.sntcca.sbcglobal.net) (Ping timeout: 264 seconds)
2020-09-24 14:00:51 → Kaivo joins (~Kaivo@ec2-15-222-231-32.ca-central-1.compute.amazonaws.com)
2020-09-24 14:01:45 → barzo joins (~hd@95.70.181.226)
2020-09-24 14:02:06 <shad0w_> [exa]: it says found a hole: _ :: ITree a -> ITree b
2020-09-24 14:02:28 hackage signable-haskell-protoc 0.2 - Deterministic serialisation and signatures with proto-lens support https://hackage.haskell.org/package/signable-haskell-protoc-0.2 (coingaming)
2020-09-24 14:02:34 <shad0w_> that should just be an (fmap g)
2020-09-24 14:02:55 × barzo quits (~hd@95.70.181.226) (Client Quit)
2020-09-24 14:03:25 → Sgeo joins (~Sgeo@ool-18b982ad.dyn.optonline.net)
2020-09-24 14:03:57 hackage signable 0.2 - Deterministic serialisation and signatures with proto-lens support https://hackage.haskell.org/package/signable-0.2 (coingaming)
2020-09-24 14:04:21 <shad0w_> byorgey: that was a nice exercise. i needed to grind my brain gears on that one.
2020-09-24 14:05:52 → heatsink joins (~heatsink@107-136-5-69.lightspeed.sntcca.sbcglobal.net)
2020-09-24 14:06:26 <[exa]> shad0w_: yeah, that should work :]
2020-09-24 14:07:05 <shad0w_> [exa]: Thanks for the help : )
2020-09-24 14:07:26 <[exa]> shad0w_: anyway, you can look at the whole construction now as "getting through layers" -- you strip and re-do the Leaf and Node "tags", then you use whatever is needed to get into/modify the inner type
2020-09-24 14:07:27 × kori quits (~kori@arrowheads/kori) (Read error: Connection reset by peer)
2020-09-24 14:08:04 <[exa]> onion approach works quite well for this kind of exercises, and when you don't know, just leave a _ .
2020-09-24 14:08:22 → tzh joins (~tzh@2601:448:c500:5300::82b3)
2020-09-24 14:08:55 <shad0w_> getting fimiliar with the type signatures is what really helps me in the end
2020-09-24 14:08:59 → kori joins (~kori@arrowheads/kori)
2020-09-24 14:09:15 <shad0w_> okay i need to go from here -> here via this and this and then that
2020-09-24 14:09:32 <[exa]> yeah there's a general approach to "just follow the types"
2020-09-24 14:09:51 <shad0w_> but when a types get a little nested
2020-09-24 14:10:04 → nineonine joins (~nineonine@216-19-190-182.dyn.novuscom.net)
2020-09-24 14:10:05 <shad0w_> it gets hard to keep it in my brain all at once
2020-09-24 14:10:10 <shad0w_> for now.
2020-09-24 14:10:23 <tdammers> the great thing about typed languages is that you don't have to
2020-09-24 14:10:27 <shad0w_> i think it's something you get the hang of as you progress ?
2020-09-24 14:10:29 → howdoi joins (uid224@gateway/web/irccloud.com/x-pmfgngzmblrpwuzc)
2020-09-24 14:10:30 <tdammers> (keep it all in your brain at once, that is)
2020-09-24 14:10:40 × heatsink quits (~heatsink@107-136-5-69.lightspeed.sntcca.sbcglobal.net) (Ping timeout: 260 seconds)
2020-09-24 14:10:48 <tdammers> this is the real reason why people spell out types all the time even when the compiler could infer them
2020-09-24 14:10:52 <tdammers> it's just easier on the brain
2020-09-24 14:10:59 <shad0w_> i did a lot js in a previous life
2020-09-24 14:11:04 <shad0w_> don't i know that lol
2020-09-24 14:11:06 <tdammers> dump that information in the code so that the compiler can keep track for you
2020-09-24 14:11:14 → adamwespiser joins (~adam_wesp@209.6.42.110)
2020-09-24 14:11:15 <[exa]> helps a lot eg with writing monad instances and lenses for whatever
2020-09-24 14:11:30 <shad0w_> i am yet to get to those
2020-09-24 14:12:13 <[exa]> the second best thing on explicit types written everywhere is that the type errors don't escape
2020-09-24 14:12:19 × adamwespiser quits (~adam_wesp@209.6.42.110) (Remote host closed the connection)
2020-09-24 14:12:22 <tdammers> yup
2020-09-24 14:12:28 <[exa]> but you need a larger program to truly appreciate that
2020-09-24 14:13:02 <tdammers> yeah, if your code is still within the size limits of the average programmer brain, the benefit is marginal, but once you get past that point, it's super helpful
2020-09-24 14:13:05 <shad0w_> tdammers: i did a exercism exercise in nim. the mentor reponse was, remove the conrete type from the function signature. the compiler can infer it anyway
2020-09-24 14:13:15 <shad0w_> i was like:- no can do's ville, baby doll.
2020-09-24 14:13:20 <tdammers> a bit like asserts on pre- and post-conditions in imperative code, just way more accurate
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