Tooling: can one "unwrap" a function?

[benjamin-thomas]

Hello I’m following along with the guides…

Please have a look at this gist

After fiddling and trying to find a working solution, I decided it’s time to introduce a default model.name on page load.

However, I choose the wrong abstraction on line #129. So I must “revert” the 2 levels of indirection I introduced. That way, I can inject the necessary value model.name on line #130.

Choosing the wrong abstraction is quite common when coding IMO.

So I can only suppose this situation is quite common in Elm too, and it must be a bit of pain trying to “unwrap” functions similar to this one later on once your project evolved quite a bit.

So I’m wondering: are there tools that exists and can unwrap this way?

This:

textInput "Your name" SetName

Transformed into:

input_ "text" "Your name" SetName

Transformed into:

input [ type_ "text", placeholder "Your name", onInput SetName ] []

I can understand that all the information is there statically.

Sorry if this is a noobish question, I’m not quite sure what I’m looking for.

I’m using this vscode exension btw

Thanks

[ChrisWellsWood]

As far as I’m aware, it’s not possible to “unwrap” a curried function (I think that’s what you’re asking). In practice, I don’t think that this is a massive issue, mainly as refactoring is very easy in Elm. If you do something like this, I’d just change the function to something like:

textInput : { placeholder : String, value : String, inputMsg : String -> Msg } -> Html Msg

Then just follow the compiler errors until it’s refactored.

[Janiczek]

We sometimes run into this situation in our Elm codebase, and given Elm’s compiler behind our backs and helpful messages, it’s indeed enough to follow the compiler errors. It’s not daunting / painful at all but just a bit mechanical (depends on the number of usages of that function you have). That’s where Vim-fu comes up

[allanderek]

tl;dr Sorry OP I do not think what you’re after is available, but it’s a good question, maybe some IDE that I do not use (such as the intelliJ Elm plug-in which I’m told is excellent) has this feature, but I don’t know of any.

I think the respondents here have misunderstood the question. Of course maybe it’s me who is misunderstanding. I believe the OP is talking about a situation in which you have developed a ‘convenience’ function. As he has done a textInput function:

textInput : String -> (String -> Msg) -> Html Msg
textInput currentValue onInput =
      Html.input
            [ Attributes.type_ "text"
            , Attributes.value currentValue
            , Events.onInput onInput
            ]
            []       

So it’s just a little convenience function, maybe you have a bunch of text inputs so you have something like:

Html.form
     [ Events.onSubmit .... ]
     [ textInput model.name NameInput
     , textInput model.email EmailInput
     , textInput model.petsName PetsNameInput
     , ... etc
     ]

Now you realise, that you want the email input to have input type email rather than text, and you want it to have a placeholder. So all he wants is an editor command that would simply inline the current function, so that the above would be replaced with:

Html.form
     [ Events.onSubmit .... ]
     [ textInput model.name NameInput
     , Html.input
            [ Attributes.type_ "text"
            , Attributes.value model.email
            , Events.onInput EmailInput
            ]
            []       
     , textInput model.petsName PetsNameInput
     , ... etc
     ]

So that he can then edit the Html.input and change the input type and add a placeholder attribute. So the word you were looking for was “inlining” as opposed to “unwrap”.

So he’s basically after refactoring support from the editor. I don’t believe this particular support yet exists, but it’s a good question, this does come up.

[opvasger]

@benjamin-thomas

are there tools that exists and can unwrap this way?

not as far as I know, but it could be a lot of fun to hack on a tool for it (and maybe more?).

Perhaps using Elm itself, this parser-module, and a Node.js CLI-wrapper, to quickly get started:

1. Parse some modules
2. Perform some rewrite-rules
3. Dump it back into some files

Let me know if you’d like to try something along these lines

[benjamin-thomas]

Thanks all

Of course when I was talking about “pain” I was exaggerating : the tooling is already very nice. In parallel, I am trying the intellij plugin too and it it is indeed very nice, less noisy than the vscode one.

@Janiczek I’m a vimmer too don’t worry, I guess I was having a full on lazy moment ^^

@allanderek that’s right, “inlining” feels like the right term. I’d imagine an editor command that would “inline” the code one level up (or is it down? ) upon each keypress.

opvasger this look like a very interesting package. I think this language is clicking with me so I’ll stick to digging into it more for now but I’ll definitely keep this in mind for later thanks.

[razze]

Should be fairly simple in the language server, if somebody want’s to address this.

I can mentor.