Adding a Methods type to Selectable, similar to Fields

Language Design
1

Trying to provide a Selectable but for structs made out of vars, I find that Fields works really nice for applyDynamic, but I get nothing for selectDynamic. Given the existence of named tuples, it wouldn’t be hard to synthesize something like

// given
case class Point(x: Int, y: Int)
// produce
Selectable {
  type Fields = (x: Int, y: Int)
  type Methods = (x_= : (Int => Unit), y_= : (Int => Unit))
}

using the metaprogramming tools.

Alternatively, lacking this, I’m forced to, using just Fields, return some W[ActualType] for every field, and then provide an awkward := or similar operator to properly handle the operation.

2

Is the point here that Fields only ever delegates to selectDynamic? So you don’t want to return closures but still need to support dynamic method calls

3

I need to support vars basically, because structs behave like that, and I have no decent mechanism to do the “setters” because they are foo_=(v) methods.

1 Like
4

Ok gotcha specifically mutable fields, good point