I get the same results as you with perl v5.38.2.

These two work for me: 

palt 'Math::BigInt'->new(123456);
palt +Math::BigInt->new(123456);

[download]

Update: so long as I define (or pre-declare) sub palt before making these calls.

Is there some technique that will allow me to make that (failing) call work - without having to place that argument in brackets ?

Curious to know why you need to do that - XY Problem? 

👁️🍾👍🦟

In reply to Re: Calling a sub without enclosing its argument inside brackets by eyepopslikeamosquito
in thread Calling a sub without enclosing its argument inside brackets by syphilis

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