On Wed, Oct 3, 2018 at 22:21 ToddAndMargo <toddandma...@zoho.com> wrote:
> >> On 04/10/2018 03:07, ToddAndMargo wrote: > >>> Hi All, > >>> > >>> In another thread, Timo wrote me: > >>> > >>> The "-->" part of the signature is optional. If there isn't > >>> one, it defaults to Mu, which is the type that everything > >>> conforms to, i.e. the sub or method that either has "--> Mu" > >>> explicitly, or has it by leaving it out, may return > >>> absolutely whatever it wants. > >>> > >>> After all, the "-->" part is a constraint, and it gets > >>> validated at compile time every time a sub or method > >>> returns. > >>> > >>> I got to thinking, some routines do not return anything. Without > >>> the "-->" constraint, how am I to determine if something is > >>> being returned? > >>> > >>> Yours in confusion, > >>> -T > > On 10/3/18 6:44 PM, Timo Paulssen wrote: > > I just spotted a grave mistake in my earlier mail: > > > > the --> constraints are validated at *run* time, not *compile* time; > > that's a very big difference, and an important one. Of course "every > > time a sub or method returns" doesn't make much sense if i had meant > > "compile time", but I felt i should really point it out before causing > > too much confusion. > > > > Hi Timo, > > Thank you for the help over on the chat line with IN! > > My confusion is not that it returns something (Mu). > > My confusion is "what" it returns. I'm not clear on what you mean. When "--> XXX" is given, then an XXX is returned. When no "-->" is given, it technically returns Mu but you can pretend it is like a Pascal/Module "procedure" that does not return anything. And not all subs > return things, like "say" and "print". That's not the case. "say" and "print" return something that conforms to --> Bool:D (in most cases, True). > > I am presuming I am to pick the "what" from context > from the examples? What context or examples are you referring to? Both docs rather clearly state that True is typically returned, and in the case of https://docs.perl6.org/routine/say the very second code example states this in English and then shows it with an example. > > -T > > > -- > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > Computers are like air conditioners. > They malfunction when you open windows > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >
