Simon,

zimoun 写道：
> Instead of hint, I propose this patch which displays:

Perfect!  That's what I wanted to write, but couldn't :-)

(I still don't really understand THROW and friends, or what 
exactly your snippet does, but the output is exactly what I had in 
mind.)

Thanks!  LGTM, obviously.

> the ’match’ can be avoided

True, but I chose it deliberately, and still prefer it over CAR or 
equivalent.

Kind regards,

T G-R