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Re: .kv ?

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From:
Todd Chester
Date:
September 14, 2018 11:21
Subject:
Re: .kv ?
Message ID:
f22c8ca5-4d69-6aeb-994a-81715c1bb9c7@zoho.com
>> On Fri, Sep 14, 2018 at 7:08 AM Todd Chester <ToddAndMargo@zoho.com 
>> <mailto:ToddAndMargo@zoho.com>> wrote:
>> 
>> 
>> 
>>     On 09/14/2018 04:01 AM, Simon Proctor wrote:
>>      > :D is a type constraint requiring an instantiated (or defined)
>>     object of
>>      > the given type (or a subtype of it).
>>      >
>>      > :U is a type constraint saying you have a container specified for
>>     the
>>      > given type that hasn't been instantiated.
>> 
>>     Hi Simon,
>> 
>>     Your went over my head.  What the heck is "instantiated"?
>> 
>>     https://www.dictionary.com/browse/instantiate
>>     verb (used with object), in·stan·ti·at·ed, in·stan·ti·at·ing.
>> 
>>           to provide an instance of or concrete evidence in support
>>           of (a theory, concept, claim, or the like).
>> 
>>     I am not connecting the dots.
>> 
>>     Is there a list of these guys somewhere, or are these the only two?
>> 
>>     -T
>> 



On 09/14/2018 04:16 AM, Curt Tilmes wrote:
> See 
> https://docs.perl6.org/type/Signature#Constraining_defined_and_undefined_values
> 
> If I say "my Int $x",
> $x is now an Int, but an undefined Int.
> 
> If I say "my Int $x = 42",
> $x is an Int, but set to a defined value, 42.
> 
> Both are Int:
> 
> say 42 ~~ Int; # OUTPUT: «True␤»
> say Int ~~ Int; # OUTPUT: «True␤»
> 
> 
> There are three type constraint suffixes you can add -- :D (defined), :U 
> (undefined) or :_ (defined or undefined)
> 
> # Checking a type object
> say Int ~~ Any:D; # OUTPUT: «False␤»
> say Int ~~ Any:U; # OUTPUT: «True␤»
> say Int ~~ Any:_; # OUTPUT: «True␤»
> # Checking an object instance
> say 42 ~~ Any:D; # OUTPUT: «True␤»
> say 42 ~~ Any:U; # OUTPUT: «False␤»
> say 42 ~~ Any:_; # OUTPUT: «True␤»
> 
> 
> 

Hi Curt,

Beautiful explanation!  I am writing it down tomorrow
in my keepers file.

Thank you!

-T

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