You're on the right track. You want something like: 
    @array does role {
        method insert ($x) {
            @.push($x) unless any(self) eqv $x;
        }
    }

[download]
Arguably we could provide syntactic sugar to reduce that to: 
    @array does method insert ($x) {
        @.push($x) unless any(self) eqv $x;
    }

[download]
Perhaps that use of does is redundant with but= and could be removed, but it does read better, I think. In any case, doing an operation like this on an object ends up creating an anonymous class that derives from the original class and adds in the extra method, so you don't clobber the original Array class.

In reply to Re^2: [Perl 6] Object methods on the fly? by TimToady
in thread [Perl 6] Object methods on the fly? by blazar

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