let's try a proposal as thought experiment and discuss it

---

short version:*

• basically only file and function scope are automatic.
• all deeper nested scopes need to be explicit. Implicit effects there - if allowed - belong to the surrounding file/function scope.
• nested subs are tricky

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1. Any assignment to an undeclared new variable implies a "implicit" my when in

• file-scope (outside any sub)

  $x = 1 ==> my $x =1

• function-scope

  sub foo { $x = 1; ... } ==> sub foo { my $x =1; ... }

• loop-header but NOT body

  for $x (@a) {...} ==> for my $x (@a) {...}

• some commands like open *

  open $fh, ... ==> open my $fh, ...

2. explicit my are still optionally allowed, our and state keep their semantics

3. No hoisting, a variable accessed before an implicit my still belongs to the upper scope and needs to be declared there

4. loop-bodies and naked blocks (technically the same) follow the old rules

• to restrict the scope of a var you'll still need an explicit my
• an implicit my (i.e. assignment to a new var) belongs to the outer scope, starting with the block

  { $x=42 }; print $x; => 42

5. ( ??? ) nested/anonymous subs are tricky, when it comes to closed over vars

• if they follow rule 1, than we need a declaration alike Py's nonlocal ... maybe its or over to mark vars avoiding implicit my
• if they are exempt from rule 1 and rather act like 4, we get a break in symmetry
• another solution would be a new keyword fun to create a sub with auto-mine while keeping sub explicit.

6. ( ??? ) functional blocks like in map {BLOCK} are technically anonymous subs °

• see point 5

7. ( ??? ) class-variables are a current issue in proposed new OOP models.

8. special global vars are exempt from implicit my.

9. Last but not least automine activates strict

So ...

• Did I forget a case?
• Do you need examples?
• Please inform yourself about closures before judging.

°) actually not in the case of map and grep but for all of List::Util , try return to see the difference

*) updated