a'b ambiguous with a'[1,1]

[zsoerenm]

Today I stumbled over this ambiguity:

a = [2, 1]
b = [1, 1]
a'b # outputs 3
a'[1, 1] # outputs 2

a'[1, 1] here is the first entry of a'.
What's the purpose of the syntax a'b instead of a' * b? Could the syntax a'b be removed to avoid this ambiguity?

[Keno]

I think the second of these should be disallowed as ambiguous and parentheses required.

[JeffBezanson]

The thing is, as far as I know it's never possible to juxtapose an expression with [...], since that is by definition the syntax for indexing. So this doesn't bother me too much. We could disallow the special case of x'[ ] I guess, since that's probably rarely used, but still technically breaking.

[oscardssmith]

triage thinks deprecation is the right answer here.