Jonathan Lang wrote:
Please, no attempts to merge signatures.  Instead, use multiple

That avoids the problem before it occurs. But do you expect
every role to provide its methods as multi just in case?

Also, sub is an odd choice to use while illustrating role composition;
while subs _are_ allowed in roles AFAIK, they're generally not put
there.  Methods and submethods are by far more common.

The problem remains the same. After method lookup the arrow type of
the non-invocant parameters has to be a contra-variant supertype of
the two merged signatures. This signature is then a requirement to
the composed class that indirectly does both roles.

Regards, TSa.

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