Some way to set a default callback

[sgued]

It appears that it is currently not possible to set a default callback in a global export or for a component.

This would be very useful to have some indication (using debug) that a callback has been called when using the viewer. This is especially important for callbacks that return a value, where the viewer's on argument cannot return anything. This would help ensure that the callback is properly called.

For example an app that parses hexadecimal and prints ascii. You would create a pure callback parse(string) -> string so that it can be implemented in the host language, but for fast iteration with the viewer it would be appreciable to define a default callback, even if it mocks the actual logic of the callback and just returns some debug value that shows it has been called.

[ogoffart]

I think you can do that, for example:

export component Foo {
 pure callback parse(string) -> string
 parse(x) => { return x; }
}