Effect widening doesn't occur for effect parameters

[timbertson]

I'm not sure if I'm describing it right, but here's a simple example where a structure has a parameterised effect:

// lazy.kk

struct lazy<e, a>
  compute: () -> e a

fun get(l: lazy<e, a>): e a
  l.compute.()

fun pure<a>(value: a): lazy<total, a>
  Lazy { value }

fun map(l: lazy<e, a>, f: (a) -> e b): lazy<e, b>
  Lazy { f(l.get) }

But attempting to introduce console in a map call doesn't work:

fun main()
  val a = pure(1)
  val b = a.map fn(i)
    println("mapping over " ++ i.show)
    i.show
  
  val result = b.compute.()
  println("result: " ++ result)

I get:

std/lazy.kk(15,21): type error: effects do not match
  context        :                 fn(i)
                       println("mapping over " ++ i.show)
                       i.show
  term           :                     
                       println("mapping over " ++ i.show)
                       i.show
  inferred effect: <console/console|_e>
  expected effect: total
  unexpected     : console/console

If this were a regular function koka would simply widen the pure function's effect into a console function, is there a way to get this to happen with effect type params?

---

Incidentally, I don't understand the error when I mistakenly use <total> instead of total when giving a type to a (it works fine as lazy<total,int>):

	val a: lazy<<total>, int> = pure(1)

// error:
std/lazy.kk(14,31): type error: types do not match
  context      :       a
  term         :                               pure(1)
  inferred type: lazy<total,int>
  expected type: lazy<total,_a>
  because      : type cannot be instantiated to match the annotation

That definitely sounds like a problem with the value type, not the effect. I get the same if I try to manually widen the type to e.g. <div,console>

[timbertson]

Possibly related / similar to #519