Implement namespaced constructors and operations

[b-studios]

Constructors and operations are now defined in a namespace, named after the type.

For instance:

type TrafficLight { Red(); Green(); Yellow() }

defines the constructor TrafficLight::Red, but also imports it as Red. The same holds for operations, which can now (in principle) be disambiguated like cap.Nondet::flip().

As a drive-by, I simplify the way operations are looked up and drop the unused effect on Do, which was in preparation for do Nondet.flip(), which now is do Nondet::flip().

[b-studios]

@timsueberkrueb there is a LSP Server test failing:

==> X effekt.LSPTests.Server publishes term names in the correct order  0.555s munit.ComparisonFailException: LSPTests.scala:1782
1781:
1782:      assertEquals(outerBindings.length, 3)
1783:      assertEquals(outerBindings(0).name, "e1")
values are not the same
=> Obtained
5
=> Diff (- obtained, + expected)
-5
+3

Can I just update the number or do we want the change the behavior in the server?

[b-studios]

@timsueberkrueb Could you double check w.r.t. to the "outline" and holes panel? In particular, I am afraid that operations might now show up twice (once in the namespace and once outside).

[b-studios]

Here you can see that we now can also disambiguate equally named constructors in patterns.

[timsueberkrueb]

@timsueberkrueb Could you double check w.r.t. to the "outline" and holes panel? In particular, I am afraid that operations might now show up twice (once in the namespace and once outside).

Yes, they do indeed occur twice now.

[b-studios]

I discussed this with @timsueberkrueb: Ideally, the semantics of

type Color { Red(); Green() }

is

type Color { Color::Red(); Color::Green() }
import Color::*

so the unprefixed constructors (and operations) should be listed as imports, not bindings.

[b-studios]

I implemented it, but it isn't that simple. Assume two files with the import semantics:

// color.effekt
type Color { Color::Red(); Color::Green() }
import Color::*

and

// colorpicker.effekt
import color
def chooseColor(): Color = Red()
                           ^^^^^
         Cannot find a function named `Red`.

then the "generated" import Color::* will only be applied in the scope of color.effekt, but not in colorpicker.effekt.

[b-studios]

So, backtracking, the semantics implemented previously (and which I plan to go with for now) is

type Color { Color::Red(); Color::Green() }
export Color::*

Since Red and Color::Red refer to the same symbol we can later choose which one to show. Maybe this is easier to solve once we reconsidered qualified names.