I would love apl with types.
It would definitely work though.
If there is a conflict with an existing feature you could always create a Slang. A Slang is a module that changes the parser. (It could be argued that with this feature all programming languages are a subset of Perl 6)
https://www.cs.ox.ac.uk/people/jeremy.gibbons/publications/a...
http://www.ccs.neu.edu/home/shivers/papers/rank-polymorphism...