Role-based testing seems very perl6ish. I'd suggest the role name be
"Invocable" with much the sort of signature as you've described.

That being said, I don't think that the current error is terrible. It
clearly shows that the issue is with the attempt to invoke a Bool.

Aaron Sherman, M.:
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On Mon, Nov 14, 2016 at 2:32 PM, Brandon Allbery <>

> This started out some weeks ago as a user in #perl6 confused by an error
> that gofled down to:
> [28 19:01:37] <geekosaur> m: my Bool $x = False; $x()
> [28 19:01:38] <camelia> rakudo-moar 0dc6f7: OUTPUTĀ«No such method
> 'CALL-ME' for invocant of type 'Bool'
> This is, at the very least, LTA. But it also got me thinking about the
> spec.
> The obvious way to clean up the above, and some more complicated things of
> the same sort, is to hide the obviously-internal CALL-ME behind a role,
> which arguably should be part of the spec as well to let implementations
> provide a stable interface while doing whatever is necessary for the
> backend in its implementation. The obvious name for this role is Callable.
> But, we already have a role Callable which is a mixin that adds
> functionality to things that are callable, and is part of 6.c's spec. This
> seems like a design flaw, and looks like it's going to be hard to fix, or
> at least to make rational when other roles describe things that *are*
> something instead of describing what they *modify*.
> Is there a way forward on this that makes any sense?
> (for the record, the proposed wrapper role looks something like
> role OughtToBeCallable { # bikeshed pending paint job...
>   method CALL(|c) {...}; # CALL-ME happens here
> }
> and the 4 places that currently build a CALL-ME in nqp would have a type
> OughtToBeCallable added so that the runtime CALL-ME error becomes a
> compile-time failed OughtToBeCallable constraint with a
> user-comprehensible error.)
> --
> brandon s allbery kf8nh                               sine nomine
> associates
> unix, openafs, kerberos, infrastructure, xmonad

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