Dynamically type-casted variables cannot be used to build streams with map()

[renatoathaydes]

In this code, I define a small interface to represent a HTML element that has text, then attempt to build a stream of it.

interface HasText {
    shared formal variable String textContent;
}

dynamic {
    {HasText*} textItems;

    dynamic doc = window.parent.document;
    dynamic nodes = doc.getElementsByTagName("A");
    Integer nodesLength = nodes.length;
    textItems = (0..nodesLength-1).map((Integer i) {
        HasText elem = nodes.item(i);
        String oldText = elem.textContent;
        print(oldText);
        return elem;
    });
... 
}

This, when run with the Beta Web IDE, throws a type error:

Runtime error:
--- TypeError: Expected web_ide_script::run.HasText (new1.ceylon 20:23-20:35)

This should work, because If I change the type of the Stream to {String*} and build a stream by calling textContent on each element, then it does work... so it seems it's a bug in not recognizing a custom type.

[lucaswerkmeister]

I don’t think that’s a bug. It works if you make HasText a dynamic interface: http://trybeta.ceylon-lang.org/?gist=03d6a0375eb1af63442a

[gavinking]

Right, this is exactly what dynamic is for, isn't it.

[renatoathaydes]

But does that mean it work for String because it's treated as a dynamic type?

[gavinking]

Well strings and numbers are special, because there is a built-in mapping between JS and Ceylon types.

[chochos]

Indeed, you need to make HasText a dynamic interface.

[FroMage]

Sounds like not a bug, closing.