On 10/3/18 7:53 PM, Trey Harris wrote:
On Wed, Oct 3, 2018 at 22:21 ToddAndMargo <toddandma...@zoho.com
<mailto: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.
My misunderstanding! Even the home spun ones "--> Bool".
Thank you!
$ p6 'sub x($Str) {say $Str};say x("y");'
y
True
Now all I have to figure out is what exactly is being
returned in Mu
