Code position effect

[marzipankaiser]

This allows functions (and effects etc) to require a codepos effect from their context, which is implicitly handled at each call site of such a function and returns a unique string for that call site.

This is (ab-)using effects for something similar to the implicit parameters in

Daan Leijen, Tim Whiting: Syntactic Implicit Parameters with Static Overloading

[marzipankaiser]

This now has the following (rough) semantics:

• If a function has a codepos effect, it is implicitly handled at the callsite by returning a constant String
  • except if it is in a context where codepos is handled already, i.e.:
    • in a try { .... } with codepos {...}
    • in a def ... : ... / { ..., codepos, ... } =
    • in a higher-order function call that handles codepos

This allows "forwarding" the code position to helper functions easily.

[marzipankaiser]

Superseded by #1380 .