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elmlang | general | Both key and value of a dict must a of _one_ specific type. I know now other way to achieve this, other with a new type that wraps multiple types. | 2019-01-04T16:45:49.551300 | Timika |
elmlang | general | If `Dict` would allow multiple kinds of type as value at the same time, how would you know what type `Dict.get "key"` results in? :slightly_smiling_face: | 2019-01-04T16:46:43.552300 | Timika |
elmlang | general | <@Nery> Are you asking in general or is there a specific problem you want to solve? | 2019-01-04T16:47:28.553100 | Monte |
elmlang | general | <@Monte> is asking the real questions here :slightly_smiling_face: | 2019-01-04T16:48:00.554200 | Timika |
elmlang | general | well a generally approach i take in other languages is to model my data based on a vocabulary of facts
and these usually go into a Dict-like structure but obviously the types vary | 2019-01-04T16:48:01.554300 | Nery |
elmlang | general | so it would be great to be able to say "age" is Int | 2019-01-04T16:48:30.554900 | Nery |
elmlang | general | Correct me if I’m wrong, but would that not be a record? | 2019-01-04T16:48:42.555400 | Timika |
elmlang | general | to put the type on the _key_ itself, eg | 2019-01-04T16:48:46.555500 | Nery |
elmlang | general | ...which you can get with _records_, i realize but then i have to create a huge type taxonomy or something ... ie, that's cheating cos it's not on the key the type of the key is for that record only | 2019-01-04T16:49:24.556600 | Nery |
elmlang | general | Can you give an example what you mean by “model my data based on a vocabulary of facts”? | 2019-01-04T16:50:05.557300 | Timika |
elmlang | general | well here's an example... i want a function like
`isOldEnough()` | 2019-01-04T16:50:21.557800 | Nery |
elmlang | general | `isOldEnough : Entity -> Boolean` | 2019-01-04T16:50:35.558200 | Nery |
elmlang | general | ```isOldEnough : { a | age : Int } -> Bool
isOldEnough { age } =
age >= 18``` | 2019-01-04T16:51:12.559000 | Timika |
elmlang | general | wherein isOldEnough could be defined as such:
`isOldEnough = get "age" Entity > 21` | 2019-01-04T16:51:13.559200 | Nery |
elmlang | general | would be a way to do this with records | 2019-01-04T16:51:20.559400 | Timika |
elmlang | general | gotcha | 2019-01-04T16:51:26.559700 | Nery |
elmlang | general | Relevant to programming with maps <https://mobile.twitter.com/EvilHaskellTips/status/433449719226826752> | 2019-01-04T16:51:36.560200 | Kris |
elmlang | general | then you can pass in every record with an `age` field. | 2019-01-04T16:51:36.560300 | Timika |
elmlang | general | with an `_Int_``age` field | 2019-01-04T16:51:59.561000 | Nery |
elmlang | general | cool | 2019-01-04T16:52:01.561200 | Nery |
elmlang | general | Correct, yes. | 2019-01-04T16:52:06.561400 | Timika |
elmlang | general | <@Kris> okay that evil tip has got me intrigued | 2019-01-04T16:52:41.562300 | Nery |
elmlang | general | thx <@Timika>.. i know that's newbie stuff. i prolly should be in <#C192T0Q1E|beginners> on that question .. thank you | 2019-01-04T16:53:06.562800 | Nery |
elmlang | general | No worries! Happy to help wherever I can! :slightly_smiling_face: | 2019-01-04T16:53:32.563300 | Timika |
elmlang | general | Yeah, cake! :slightly_smiling_face: | 2019-01-04T16:55:42.563800 | Timika |
elmlang | general | another pesky question...
what's the significance of requiring `age` to be defined in record after record
why couldn't age simply be defined as Int w/o marrying it to a record
are there strongly typed PLs that allow stuff like this.
it seems rather silly or redundant to have to keep re-defining `age` across N records as an Int
(i assume haskell makes you do the same thing?) | 2019-01-04T16:59:00.565900 | Nery |
elmlang | general | I don’t understand your question, but you can just write that function as an `Int -> Bool` and call it as `f myRecord.age` | 2019-01-04T17:00:41.568300 | Kris |
elmlang | general | Haskell doesn’t really have records, so nope : p | 2019-01-04T17:00:55.568900 | Kris |
elmlang | general | but what if my logic is based on not just age, eg
`canRideThisRide : Entity -> Bool`
...where in you have to be 10 or older and your height has to be greater than 1.5m, say... | 2019-01-04T17:02:36.571400 | Nery |
elmlang | general | so i have `age`, an Int, and `height`, a Float, say | 2019-01-04T17:02:53.571800 | Nery |
elmlang | general | That works the same way as with my example code. You can _match_ on multiple fields. | 2019-01-04T17:03:22.572400 | Timika |
elmlang | general | Are you trying to be super generic here? Or could `Entity` be a record that has all the fields you want:
```
type alias Entity =
{ age : Int
, height : Float
, name : String
, ...
}
``` | 2019-01-04T17:04:06.573300 | Carman |
elmlang | general | ah i like that <@Carman>
would that be acceptable approach or .. an anti-pattern..? | 2019-01-04T17:05:00.574400 | Nery |
elmlang | general | Then you could say:
```
canRideThisRide : Entity -> Bool
canRideThisRide entity =
entity.age > 10 && entity.height < 1.5
``` | 2019-01-04T17:05:00.574500 | Carman |
elmlang | general | i mean that's basically what i'm after <@Carman> | 2019-01-04T17:05:34.575400 | Nery |
elmlang | general | i want to define a _vocabulary_ | 2019-01-04T17:05:40.575800 | Nery |
elmlang | general | It would become an anti-pattern as soon as you have fields that are not used by all kinds of entities and then get a default value that makes no sense. | 2019-01-04T17:05:50.576300 | Timika |
elmlang | general | NOT a taxonomy of types | 2019-01-04T17:05:52.576400 | Nery |
elmlang | general | I'd say that's the standard way to design structures. As your business rules get more complex you can get fancier to eliminate impossible states | 2019-01-04T17:05:59.576500 | Carman |
elmlang | general | ah <@Timika> that seems a problem | 2019-01-04T17:06:24.576800 | Nery |
elmlang | general | can they just be defaulted to Empty/Null/what-have-you? | 2019-01-04T17:07:16.577900 | Nery |
elmlang | general | Unknown | 2019-01-04T17:07:27.578200 | Nery |
elmlang | general | You could make them `Maybe`s. But I would consider a record with just `Maybe` values an anti-pattern. But as always, you have to make your own trade-offs that make sense to you and the problem you’re trying to solve. | 2019-01-04T17:08:12.579100 | Timika |
elmlang | general | yeah i guess my issue is that this seems pretty basic | 2019-01-04T17:08:35.579700 | Nery |
elmlang | general | so i have a sense i'm missing something | 2019-01-04T17:08:40.580000 | Nery |
elmlang | general | Could it be that you’re trying to do some game-engine stuff? :slightly_smiling_face: | 2019-01-04T17:08:49.580200 | Timika |
elmlang | general | hahaha that would be more fun than what i'm doing | 2019-01-04T17:08:58.580600 | Nery |
elmlang | general | i'm basically just doing business data processing stuff | 2019-01-04T17:09:13.581200 | Nery |
elmlang | general | Elm doesn’t have that many language features | 2019-01-04T17:09:20.581600 | Kris |
elmlang | general | like load a bunch of entities and then render them - basic stuff like that | 2019-01-04T17:09:26.581900 | Nery |
elmlang | general | but to be able to just deal w/ facts like "age" and "height" seems pretty fundamental
so, since Dicts don't really make this natural, it seems _records_ are the way to go
well, more specifically, a _single_ record like Entity seems the way to go | 2019-01-04T17:10:34.583500 | Nery |
elmlang | general | but then having say 100 fields that are all Maybe doesn't sound right
so i feel like i'm stuck between a rock and a hard place | 2019-01-04T17:11:13.584400 | Nery |
elmlang | general | It depends on what the business rules of your system are. Are there some combinations of missing/present data that are invalid? | 2019-01-04T17:13:20.587000 | Carman |
elmlang | general | not necessarily or minimally
after all is just to render | 2019-01-04T17:13:43.587500 | Nery |
elmlang | general | so if a fact isn't present then it just doesn't need to render | 2019-01-04T17:13:51.587900 | Nery |
elmlang | general | If all the Maybes are independent, it could be that you're just dealing with highly uncertain data | 2019-01-04T17:14:29.588600 | Carman |
elmlang | general | well today it's well-known but i'm worried that as new writers want to come into the data system they'll end up breaking my code if i don't make everything Maybe | 2019-01-04T17:15:12.590000 | Nery |
elmlang | general | The compiler will tell them if they need to add a Maybe | 2019-01-04T17:16:23.590700 | Carman |
elmlang | general | If all the values are guaranteed to be there today then I wouldn't bring in Maybe | 2019-01-04T17:16:53.591200 | Carman |
elmlang | general | they're serving up from back end code (no elm) | 2019-01-04T17:17:06.591500 | Nery |
elmlang | general | if i don't make them Maybe.. they could break me overnight | 2019-01-04T17:17:24.591800 | Nery |
elmlang | general | if only i could freeze time... : ) | 2019-01-04T17:17:37.592200 | Nery |
elmlang | general | Elm doesn't trust data that comes from APIs. If you're decoding JSON, it will tell you if the data is not in the right shape | 2019-01-04T17:18:28.593100 | Carman |
elmlang | general | That seems to be your core problem. You’re reading data from a source that changes at-will. How could you ever work with data from such a source? This goes way beyond types. | 2019-01-04T17:19:49.594900 | Timika |
elmlang | general | the source has the guarantee that all the facts are of the right type
like age is Int, height is Float, etc... | 2019-01-04T17:20:33.595400 | Nery |
elmlang | general | it just won't guarantee which facts you will get across the board | 2019-01-04T17:20:50.595800 | Nery |
elmlang | general | Ah, so all the facts are optional in the API? | 2019-01-04T17:21:04.596400 | Carman |
elmlang | general | i'd say if i didn't make that assumption i'd be making myself unnecessarily brittle and easily breakable | 2019-01-04T17:21:27.597200 | Nery |
elmlang | general | like my customers want access to their data in all cases | 2019-01-04T17:21:58.598000 | Nery |
elmlang | general | like if i only have a guy's first name or last name they want to see that | 2019-01-04T17:22:09.598400 | Nery |
elmlang | general | not only see it if i just have his first or last name only (for example) | 2019-01-04T17:22:19.598900 | Nery |
elmlang | general | you might want to use a more general data structure then | 2019-01-04T17:23:32.599800 | Lashawnda |
elmlang | general | i think that's what i'm looking for @luke | 2019-01-04T17:23:52.600300 | Nery |
elmlang | general | but what is it if it's not a Dict or record(s) | 2019-01-04T17:24:04.600600 | Nery |
elmlang | general | then it's time to model it with a custom type :slightly_smiling_face: | 2019-01-04T17:24:26.601200 | Lashawnda |
elmlang | general | but how .. i mean i want something like a heterogenous Dict .. is there a good pattern (ie, custom type) to get that kind of data structure? | 2019-01-04T17:24:55.602100 | Nery |
elmlang | general | The initial idea with a `Dict` and the custom type that encapsulates different types in one type seems one solution. | 2019-01-04T17:24:58.602200 | Timika |
elmlang | general | ah yeah that sounds like a good start | 2019-01-04T17:25:27.602800 | Lashawnda |
elmlang | general | <@Timika> i think you're right that initial pitch you have that's probably my best best | 2019-01-04T17:25:33.603000 | Nery |
elmlang | general | bet | 2019-01-04T17:25:35.603200 | Nery |
elmlang | general | cool i'm going to work with that for a while and see how it plays out | 2019-01-04T17:25:46.603500 | Nery |
elmlang | general | really appreciate the help | 2019-01-04T17:25:49.603700 | Nery |
elmlang | general | <more cakes> : ) | 2019-01-04T17:26:06.604000 | Nery |
elmlang | general | So, I think I came up with something | 2019-01-04T17:35:14.604200 | Huong |
elmlang | general | I am quite late to the party but if you haven't already tried that I can recommend the `airbnb` eslint config. It's also opinated but has less weird things like the semi colons in `standard` | 2019-01-04T17:38:06.604500 | Freda |
elmlang | general | <https://www.npmjs.com/package/eslint-config-airbnb> | 2019-01-04T17:40:17.604700 | Freda |
elmlang | general | <@Lynne> you mentioned wanting to use `Tree.Zipper` with a root-less forest of trees earlier - I realized that it wouldn't be super-hard to make that possible, and it would provide more consistent behaviour for `prepend` and `append`, too, so, here you go: <https://package.elm-lang.org/packages/zwilias/elm-rosetree/latest/Tree-Zipper#fromForest> | 2019-01-04T17:42:21.606300 | Huong |
elmlang | general | Need help on calling multiple function on a list while passing down the new list to the next function, I have abour 15 functions to call and apply filters and code is getting too large, so here is the example updatedRearAxleWeightFitlerList =
(uiModel.selectedFilterBullets, model.truckList)
|> filterBySalesStatus
|> filterByYear
|> filterByMake
|> filterByModel
|> filterBySleeperRoof
|> filterBySleeperBunk
|> filterByEngineMake
|> filterByTransType
|> filterBySuspension
|> filterByBodyType
|> filterByRearAxleType
|> filterByTruckType
|> filterByFleetCode | 2019-01-04T19:09:24.608200 | Ron |
elmlang | general | is there a way to list those functions in a List and map over that list call each func and passdown the result to the next func call ? | 2019-01-04T19:10:22.609400 | Ron |
elmlang | general | Yeah, there is. Need help finding it? | 2019-01-04T19:10:58.610800 | Niesha |
elmlang | general | Oh, that would be great, because I have 20 more filters to apply | 2019-01-04T19:11:30.611500 | Ron |
elmlang | general | jesus | 2019-01-04T19:11:37.611800 | Danika |
elmlang | general | You could a) extract the filter functions into `(a -> Bool)` and then it's rather easy to compose them | 2019-01-04T19:11:53.612200 | Niesha |
elmlang | general | or b) your `filterByX` are of type `List a -> List a`, in which case you wanna `foldl (>>) [filterByX, filterbyY]` (or `(<<)`) | 2019-01-04T19:13:12.613600 | Niesha |
elmlang | general | thanks, I tried foldl, it didnt work, probably I didn't do it right, let me give a try again. | 2019-01-04T19:15:30.614400 | Ron |
elmlang | general | Wait, I don't think `>>` is the right way to go here | 2019-01-04T19:16:14.614800 | Niesha |
elmlang | general | <https://klaftertief.github.io/elm-search/?q=(a%20-%3E%20a)%20-%3E%20(a%20-%3E%20a)%20-%3E%20(a%20-%3E%20a)> | 2019-01-04T19:16:15.615000 | Niesha |
elmlang | general | you need this function, doesn't seem to exist yet | 2019-01-04T19:16:23.615400 | Niesha |
elmlang | general | Nah, that's `>>`, the search just doesn't find it | 2019-01-04T19:17:28.615700 | Niesha |
elmlang | general | Oh hey is this like hoogle? | 2019-01-04T19:18:35.615900 | Danika |