Tutorial exercice 10 failure

[leinadsepol]

In tutorial for exercice n°10:

Now, let's write the mutable version. Notice the keywords 'mutable' placed in front of the field and the method. this.!field = value modifies object in place, much like in any other programming language.

mutable class Point {mutable x: Int, y: Int} {
    mutable fun incrX(): void {
      // TODO: increment the field 'x' by 1
      // HINT: 'this.!x = value' sets the field 'x' to 'value'
      
    }
}

A compilation error is returned regardless of the expression tested with run:

File "playground.sk", line 1, characters 15-19:
In 'Point's version of the member '!=' inherited from 'Equality'
1 | mutable class Point {mutable x: Int, y: Int} {
  |               ^^^^^
2 |   mutable fun incrX(): void {
File "tests/runtime/prelude/core/traits/Equality.sk", line 26, characters 12-13:
Cannot call this method on a readonly object
24 |
25 |   overridable readonly fun !=(other: inst): Bool {
26 |     !(this == other)
   |            ^^
27 |   }
File "playground.sk", line 13, characters 7-8:
Try annotating '==' method as 'readonly'
11 | extension class Point uses Equality, Show {
12 |   // Defining equality for a Point
13 |   fun ==(other: this): Bool {
   |       ^^
14 |     other.x == this.x && other.y == this.y    

[pikatchu]

Thanks a lot for flagging this!

So the problem is that those two functions have been made "readonly" in the standard lib, and we forgot to update the tutorial.

I fixed the problem and pushed a new version of the site.