The :D is described in Constraining argument definiteness (took me a while to find).

I guess the colon after D is the infix : operator, but I'm not 100% sure.

Mu is the base class of the class hieararchy, see Mu.

map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

In reply to Re: Raku: Function Signatures by choroba
in thread Raku: Function Signatures by 7stud

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