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| 2025-09-24 12:00:22 +0200 | <Enrico63> | Leary, I see. In this case I just had the solution in front of me for the whole time. Let me try. |
| 2025-09-24 12:00:21 +0200 | <tomsmeding> | Unhammer: whether stack is happy with that I dunno, but cabal supports that first-class |
| 2025-09-24 12:00:03 +0200 | <tomsmeding> | Unhammer: it is definitely possible to have multiple libraries in one .cabal file; at most one of them will be the "main" library (headed by `library`), the others will be sublibraries (headed by `library some-name`) |
| 2025-09-24 11:59:43 +0200 | <Leary> | Probably. It's a reasonable option anyway. |
| 2025-09-24 11:59:09 +0200 | <Enrico63> | So you're saying that I should fire an error in case there's more than 3 words, but then I should disregard those additional words, rather than hard erroring, when doing the rest of the validation. |
| 2025-09-24 11:59:02 +0200 | <Unhammer> | So as a workaround to my TH woes I can put all my tests in src/, putting them in the main library. Is it possible to have two libraries in one .cabal file? stack doesn't seem to let me build project:lib:library2, only project:lib |
| 2025-09-24 11:58:41 +0200 | <Leary> | (collecting as many warnings/errors as possible from the input is kinda the point of validation) |
| 2025-09-24 11:58:26 +0200 | <Enrico63> | Leary, I'm gonna try |
| 2025-09-24 11:58:20 +0200 | <tomsmeding> | yeah what Leary says is the key point I think |
| 2025-09-24 11:56:52 +0200 | <Leary> | Enrico63: Are you sure you don't want it to keep running? |
| 2025-09-24 11:56:13 +0200 | <tomsmeding> | not sure if Validation has a function with that functionality |
| 2025-09-24 11:56:02 +0200 | <tomsmeding> | I've never worked with Validation specifically, but `Validation e a -> a -> (a -> Validation e b) -> Validation e b` is implementable, I think -- where the loose 'a' argument is a default for when the first argument is a failure |
| 2025-09-24 11:55:38 +0200 | <Enrico63> | Leary, I've tried that, but I don't get, in the case of that failing, how to prevent the rest of the validation from running |
| 2025-09-24 11:55:04 +0200 | <tomsmeding> | perhaps not orElse since that throws away the error if it's a failure |
| 2025-09-24 11:54:25 +0200 | <tomsmeding> | oh maybe the idea is that you use `orElse`? |
| 2025-09-24 11:54:16 +0200 | <Enrico63> | Yeah, I thought the same. As in, I feel like I'd need Monad for doing what is requested, but Validation is definitely not a Monad. |
| 2025-09-24 11:54:13 +0200 | <Leary> | Enrico63: How about `hasThreeWords :: String -> Validation ()`? |
| 2025-09-24 11:53:11 +0200 | <Enrico63> | Confirm. It is Applicative, but isn't a Monad. |
| 2025-09-24 11:53:10 +0200 | <tomsmeding> | well if splitting is a partial operation (String -> Validation (String,String,String)) and parsing individual components also is (String -> Validation Arg), then you ain't gonna put them together without (>>=) |
| 2025-09-24 11:52:22 +0200 | <Enrico63> | Wait... am I under the mistaken assumption that Validation is not a Monad... ? Let me check. I rember I've explicitly read it is not. |
| 2025-09-24 11:51:35 +0200 | <Enrico63> | (Since it's the only exercise left in that batch, I could submit it and then lookup the solutions, but I want to understand first :( ) |
| 2025-09-24 11:51:32 +0200 | dhil | (~dhil@5.151.29.141) dhil |
| 2025-09-24 11:51:27 +0200 | <tomsmeding> | are you allowed to use (>>=) on Validation |
| 2025-09-24 11:50:59 +0200 | <Enrico63> | Still produce an error via `Validation`. |
| 2025-09-24 11:50:16 +0200 | <tomsmeding> | what are you supposed to do if the input string has more than 3 words? |
| 2025-09-24 11:49:38 +0200 | merijn | (~merijn@77.242.116.146) merijn |
| 2025-09-24 11:49:34 +0200 | <Enrico63> | Yes, and that's what my current implementation of `parseThreeWords` is doing. It takes a single `String`, and gives back a `Validation (String, String, String)`. |
| 2025-09-24 11:48:50 +0200 | <__monty__> | Enrico63: Don't you need to properly split the String in order to feed the correct bits to parseOp and parseIntOrVar? |
| 2025-09-24 11:48:38 +0200 | <Unhammer> | hm, but what if I put the TH in a lib … |
| 2025-09-24 11:48:05 +0200 | <Unhammer> | i already had that :-/ |
| 2025-09-24 11:46:58 +0200 | <tomsmeding> | Unhammer: it fixed some strange linking error with TH for me at some point; I think it was a different error, but who knows |
| 2025-09-24 11:46:50 +0200 | <Enrico63> | With just `parseInt`, `parseVar`, `parseOp`, I know I can implement `parseExpression`, but then it lacks the check on the number of words in the input string, which should be 3. |
| 2025-09-24 11:46:26 +0200 | <tomsmeding> | Unhammer: something unrelated with template haskell, but try adding `other-extension: TemplateHaskell` to the components in your cabal file that use the TemplateHaskell extension somewhere in the source files |
| 2025-09-24 11:46:20 +0200 | chromoblob | (~chromoblo@user/chromob1ot1c) chromoblob\0 |
| 2025-09-24 11:46:04 +0200 | chromoblob | (~chromoblo@user/chromob1ot1c) (Remote host closed the connection) |
| 2025-09-24 11:45:36 +0200 | <Enrico63> | probably `parseThreeWords` (in my first message I called it `parseExpr`, sorry) is what I've given the wrong signature to.. |
| 2025-09-24 11:45:36 +0200 | <Enrico63> | ``` |
| 2025-09-24 11:45:35 +0200 | <Enrico63> | parseExpression :: String -> Validation Expression |
| 2025-09-24 11:45:35 +0200 | <Enrico63> | ``` |
| 2025-09-24 11:45:34 +0200 | <Enrico63> | I don't know how to implement this: |
| 2025-09-24 11:45:34 +0200 | <Enrico63> | ``` |
| 2025-09-24 11:45:33 +0200 | <Enrico63> | parseThreeWords :: String -> Validation (String, String, String) |
| 2025-09-24 11:45:33 +0200 | <Enrico63> | parseOp :: String -> Validation (Arg -> Arg -> Expression) |
| 2025-09-24 11:45:32 +0200 | <Enrico63> | parseVar :: String -> Validation Arg |
| 2025-09-24 11:45:32 +0200 | <Enrico63> | parseInt :: String -> Validation Arg |
| 2025-09-24 11:45:31 +0200 | <Enrico63> | pure :: Applicative f => a -> f a |
| 2025-09-24 11:45:31 +0200 | <Enrico63> | (<|>) :: Applicative f => f a -> f a -> f a |
| 2025-09-24 11:45:30 +0200 | <Enrico63> | liftA2 :: Applicative f => (a -> b -> c) -> f a -> f b -> f c |
| 2025-09-24 11:45:30 +0200 | <Enrico63> | ``` |
| 2025-09-24 11:45:29 +0200 | <Enrico63> | That is, given these |