I’m creating a type alias to a type record, but it’s not compiling (see attached non-compiling ellie). What I’m trying to do is take a Person from Model and ignore all fields other than name, while the compiler is telling me the name field doesn’t exist, as if it’s losing the name field somehow… --…

Others have noticed in the past that type aliases to extensible records don’t seem to be fully supported: [image] Using extensible records in type aliases Learn I have a project with a lot of very similar but slightly different data types, so I’ve been making a lot of use …

Elm implementation of extensible records seems inconsistent and there is no public statement of whether it is a bug or it is intentional. Check this intellij-elm issue where this was discussed before: intellij type checker reports error in valid code …

With ExtensibleData c you idenity c as the type without the field name. So the subInit function return a type SubModel c which resolved to SubModel {age :Int}. This is not compatible with your Model where you expect SubModel { name : string, age: Int}

With ExtensibleData c you idenity c as the type without the field name . So the subInit function return a type SubModel c which resolved to SubModel {age :Int} . This is not compatible with your Model where you expect SubModel { name : string, age: Int} I thought type alias ExtensibleData c = { c…

[image] TankorSmash: I thought type alias ExtensibleData c = { c | name : String } means anything can be c , so long as it’s got name : String in it, but you’re saying this is c plus name : String . That matches my understanding as well. I generally use extensible records as “this function ta…

I think what’s happening is mixing up the use of extensible records in a function definition and the use of extensible records in aliases. The function getName : { r | name : String } -> String getName { name } = name is an example of using extensible records to say “This function expects a recor…

The problem comes indeed from this type annotation subInit : ExtensibleData c -> SubModel c Both c’s in ExtensibleData c -> SubModel c need to be exactly the same type. That’s how generic types work. Because { c | name : String } means that the c type doesn’t necessarily already have a name proper…

Extensible Records seems to be pruning fields and failing to compile

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Using extensible records in type aliases Learn	1	866	April 11, 2020
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Extensible Records seems to be pruning fields and failing to compile

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