Logs: liberachat/#haskell
| 2021-07-29 19:10:17 | <dsal> | You don't need `getX` when you have `gets` |
| 2021-07-29 19:10:19 | <dsal> | :t gets |
| 2021-07-29 19:10:20 | <lambdabot> | MonadState s m => (s -> a) -> m a |
| 2021-07-29 19:10:33 | <Drew[m]> | There's also `traverse`, rather than traversal. |
| 2021-07-29 19:10:35 | × | pfurla_ quits (~pfurla@ool-182ed2e2.dyn.optonline.net) (Quit: gone to sleep. ZZZzzz…) |
| 2021-07-29 19:10:58 | <dsal> | :t traversed |
| 2021-07-29 19:11:00 | <lambdabot> | (Indexable Int p, Traversable f1, Applicative f2) => p a (f2 b) -> f1 a -> f2 (f1 b) |
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| 2021-07-29 19:11:45 | <deejaytee> | echoone: that's been a source of difficulty for me in learning J - while at first parts of speech are useful for remembering what does what, it starts to clash later on |
| 2021-07-29 19:12:14 | <EvanR> | map seems a bit ambiguous... probably because this is a purely mathematical idea to me |
| 2021-07-29 19:12:15 | <deejaytee> | but I suppose it's better than no terminology whatsoever |
| 2021-07-29 19:12:22 | <dsal> | I've seen people get hung up on "how do I read this in English?" Such a weird concept. If I could even express my problems in English, I'd probably do that in the first place. |
| 2021-07-29 19:12:28 | <EvanR> | math doesn't really verb anything |
| 2021-07-29 19:12:51 | × | waleee quits (~waleee@2001:9b0:216:8200:d457:9189:7843:1dbd) (Quit: WeeChat 3.2) |
| 2021-07-29 19:12:54 | <roboguy_> | EvanR: what about "acting on" |
| 2021-07-29 19:13:07 | <roboguy_> | or "pulling back along" |
| 2021-07-29 19:13:19 | <EvanR> | right, group action. Sounds like a case of math people trying to get inspiration from language, like us |
| 2021-07-29 19:13:29 | <EvanR> | pullback definitely |
| 2021-07-29 19:13:33 | <EvanR> | it's verby |
| 2021-07-29 19:13:40 | <EvanR> | 'a pullback' lol |
| 2021-07-29 19:14:04 | <EvanR> | a case of math terms becoming ambiuously part-of-speeched |
| 2021-07-29 19:14:37 | × | fluffyballoon quits (~fluffybal@pat-verona-h.epic.com) (Quit: Client closed) |
| 2021-07-29 19:14:49 | <EvanR> | lens gets a lot of help from adjectives |
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| 2021-07-29 19:15:22 | × | fossdd quits (~fossdd@sourcehut/user/fossdd) (Ping timeout: 240 seconds) |
| 2021-07-29 19:15:27 | <EvanR> | but group actions, pullbacks, and lenses still aren't "doing" more or less than anything else |
| 2021-07-29 19:15:43 | → | fossdd joins (~fossdd@sourcehut/user/fossdd) |
| 2021-07-29 19:15:44 | <lechner> | Hi, how do I best print each element of an array on a separate line, prepended by a space, please? |
| 2021-07-29 19:15:48 | <dsal> | `map` is also a little weird because you can also think of it as just sort of sticking a transformation on list accessors. It doesn't *actually* build a new list after applying your function to every element in the list. |
| 2021-07-29 19:15:58 | <dsal> | lechner: mapM_ print thing |
| 2021-07-29 19:16:17 | <dsal> | Oh, if you want to add a space, you can stick one in the action there. |
| 2021-07-29 19:16:35 | <EvanR> | yes lazy evaluation makes verbing even less applicable, if you wanted to think of verbs causing the compuer to heat up and do things |
| 2021-07-29 19:16:36 | <dsal> | mapM_ (\x -> putStr " " >> print x) thing |
| 2021-07-29 19:16:38 | <roboguy_> | :t unlines |
| 2021-07-29 19:16:39 | <lambdabot> | [String] -> String |
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| 2021-07-29 19:17:32 | <EvanR> | verbs <-> do work |
| 2021-07-29 19:17:35 | × | raehik quits (~raehik@cpc95906-rdng25-2-0-cust156.15-3.cable.virginm.net) (Ping timeout: 258 seconds) |
| 2021-07-29 19:17:45 | <dsal> | @undo do work |
| 2021-07-29 19:17:45 | <lambdabot> | work |
| 2021-07-29 19:17:50 | <dsal> | There's no way out! |
| 2021-07-29 19:17:52 | <EvanR> | fix error |
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| 2021-07-29 19:19:04 | × | echoone quits (~echoone@188.74.32.13) (Quit: Client closed) |
| 2021-07-29 19:19:12 | <EvanR> | actually this entire train of thought about programming = a bunch of verbs to make stuff 'happen' in a row might be the initial key thing to tell people to forget when starting haskell |
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| 2021-07-29 19:20:54 | <dsal> | The intuition starts to break down with infinite lists, but yeah, it's helpful. It's also helpful when you do stuff like `map f . map g`. If you think about the `map` doing something, it suddenly seems expensive. If you think about it just shoving filters on the thing, you won't spend hours trying to make your code more complicated to do what RULEs can do. |
| 2021-07-29 19:21:20 | <Drew[m]> | I'm fine with thinking that `map` "maps a function over a list", that it "does stuff" |
| 2021-07-29 19:21:20 | <Drew[m]> | It just only does stuff when the stuff is needed. |
| 2021-07-29 19:21:56 | <lechner> | that's another point |
| 2021-07-29 19:21:57 | <dsal> | Sure. It's not a bad mental model, but it's not the only mental model. :) |
| 2021-07-29 19:22:25 | <EvanR> | you can get pretty far in haskell imagining code running by rewriting expressions |
| 2021-07-29 19:24:16 | <EvanR> | which is both an act and an expression of 'what this function means' |
| 2021-07-29 19:24:51 | <lechner> | dsal: should your lambda above print the array element (which are of type String) in quotes? |
| 2021-07-29 19:24:59 | <lechner> | elements |
| 2021-07-29 19:25:14 | <dsal> | lechner: Yeah, that's what `print` does. I wasn't sure what the type was. You can use `putStrLn` |
| 2021-07-29 19:25:22 | × | fossdd quits (~fossdd@sourcehut/user/fossdd) (Ping timeout: 240 seconds) |
| 2021-07-29 19:25:29 | <EvanR> | the second thing there makes it easy to see you could reverse it without causing problems |
| 2021-07-29 19:25:39 | <dsal> | lechner: It's good to understand what the parts were. :) |
| 2021-07-29 19:25:53 | → | fossdd joins (~fossdd@sourcehut/user/fossdd) |
| 2021-07-29 19:25:54 | <EvanR> | imperative programming often involves doing things that can't be reversed |
| 2021-07-29 19:26:11 | <EvanR> | e.g. updating arrays |
| 2021-07-29 19:27:19 | <maerwald> | so what's the alternative to brick on windows? |
| 2021-07-29 19:27:44 | <lechner> | dsal: could i also write mapM_ (\x -> putStrLn $ " " <> x) ? |
| 2021-07-29 19:30:25 | shapr | hops |
| 2021-07-29 19:31:20 | <[exa]> | lechner: a complimentary bit of compression: `mapM_ (putStrLn . (' ':) )` |
| 2021-07-29 19:31:37 | <Drew[m]> | <EvanR> "you can get pretty far in..." <- Isn't that to a degree what STG does? |
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| 2021-07-29 19:32:39 | <dsal> | lechner: I'll allow it. :) |
| 2021-07-29 19:32:58 | <EvanR> | you can think of it like that |
| 2021-07-29 19:33:16 | <maerwald> | so how do I use this from haskell https://github.com/migueldeicaza/gui.cs |
| 2021-07-29 19:33:24 | <dsal> | lechner: There's mapM_ and forM_ -- I think I've used the latter once. |
| 2021-07-29 19:33:26 | <dsal> | :t forM_ |
| 2021-07-29 19:33:27 | <lambdabot> | (Foldable t, Monad m) => t a -> (a -> m b) -> m () |
| 2021-07-29 19:33:33 | × | ubert quits (~Thunderbi@178.165.190.122.wireless.dyn.drei.com) (Ping timeout: 276 seconds) |
| 2021-07-29 19:33:55 | → | bontaq` joins (~user@ool-18e47f8d.dyn.optonline.net) |
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| 2021-07-29 19:34:28 | <lechner> | [exa]: so this would be my first point-free, but unfortunately I actually have to prepend muliple characters (" - "). Is that possible? |
| 2021-07-29 19:34:41 | <dsal> | lechner: Find out! :) |
| 2021-07-29 19:34:54 | <lechner> | with cons? |
| 2021-07-29 19:35:14 | <dsal> | Understand what it's doing. There's not much magic there. |
| 2021-07-29 19:35:23 | <dsal> | :t (' ':) |
| 2021-07-29 19:35:25 | <lambdabot> | [Char] -> [Char] |
| 2021-07-29 19:35:34 | <dsal> | :t putStrLn . (' ':) |
| 2021-07-29 19:35:36 | <lambdabot> | [Char] -> IO () |
| 2021-07-29 19:36:11 | <dsal> | Do you understand sections? |
| 2021-07-29 19:36:18 | <lechner> | i am doing it wrong |
| 2021-07-29 19:36:45 | <dsal> | You *can* use `:` but it'd be a little weird. |
| 2021-07-29 19:36:47 | × | Obo quits (~roberto@70.pool90-171-81.dynamic.orange.es) (Ping timeout: 252 seconds) |
| 2021-07-29 19:37:13 | → | Erutuon joins (~Erutuon@user/erutuon) |
| 2021-07-29 19:37:14 | <lechner> | mapM_ (putStrLn . (" - ":)) (Task.inputs task) gives me No instance for (Data.String.IsString Char) arising from literal |
| 2021-07-29 19:37:42 | bontaq` | is now known as bontaq |
| 2021-07-29 19:37:43 | <dsal> | So, taking a step back. |
| 2021-07-29 19:37:47 | <dsal> | :t (" - ":) |
| 2021-07-29 19:37:48 | <lambdabot> | [[Char]] -> [[Char]] |
| 2021-07-29 19:38:07 | <[exa]> | lechner: you confused "" and '', the second is only a single char that can be prepended with : |
| 2021-07-29 19:38:10 | <dsal> | I don't think that's what you want. |
| 2021-07-29 19:38:25 | <[exa]> | for strings, you need at least (" -" ++) |
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