Common Context objects for phases on core and lifted

[b-studios]

No description provided.

[marzipankaiser]

Rebased [note: There were no new changes compared to master in the previous version?] and added a first draft of a CoreContext that tracks the effekt.context.Context and some core.Declarations.

[marzipankaiser]

An alternative to the current design could also be to return, from e.g. findField, an object with methods

def isDefined: Boolean
def get: Field
def constructor: Constructor
def declaration: Declaration.Data

etc.
Pro:

• This would allow us to search through the declarations at most once for each Id
  Con:
• This is slightly more complicated.

[marzipankaiser]

Additional note on CoreContext: If the Decls in lifted stay like they are (a different type), we would probably want something like this for lifted, too.

[marzipankaiser]

If we want anything after core.Transformer not to inspect symbols, we will have to also encode builtins into the declarations/externs.

[marzipankaiser]

If we want anything after core.Transformer not to inspect symbols, we will have to also encode builtins into the declarations/externs.

I think this will be a bigger (-ish) and somewhat separate change, and thus make a separate PR for it.

[b-studios]

Otherwise it LGTM