Guessing game

David Bovill david.bovill at gmail.com
Tue Apr 3 05:35:48 EDT 2018


True - I’d rather be first-class than complete anyway.

And yes thanks for suggested way around incompleteness. I still suffered
culture shock. The use-case I had was to replace send syntax with the more
elegant set the ... of object to syntax. I found myself wanting a bit more
power ...

Power is not always a good thing. I’m glad that the dignity of arrays has
been restored.

On Tue, 3 Apr 2018 at 10:25, Mark Waddingham via use-livecode <
use-livecode at lists.runrev.com> wrote:

> On 2018-04-03 10:28, David Bovill via use-livecode wrote:
> > Arrays as first class citizens? Give them a passport! Arrays have
> > rights
> > too!
> >
> > Need to check if they can be passed as parameters in setprop handlers -
> > as
> > in “set the beautiful_Colour [spellingArray] of my card to light-grey”
>
> Heh - okay let me define what I mean by 'first-class citizen'...
>
> A 'thing' in a programming language is a 'first-class citizen' if it can
> be placed in a variable, and further being then able to use that
> variable to be able to access the functionality of 'thing' instead of
> referencing 'thing' directly. i.e. 'thing' can be indirected.
>
> The above example confuses two things - the idea of being first-class,
> and the ability to use a given type of value in a given context. SetProp
> handlers are defined to take a string argument, as they are backed by a
> LiveCode array (custom property set) if there is no handler to call (or
> if messages are locked). So that's just a case of functionality which
> has not been defined nor implemented.
>
> Perhaps the best example of a language feature which is nearly never
> 'first-class' (as in, I don't believe there are any widely used general
> programming languages which allow it) is types. e.g. You can't do things
> like the following:
>
>    put integer between 1 and 3 into tIntBetween1And3Type
>    put tMyString as tIntBetween1And3Type into tIntBetween1And3
>
> Certainly you can approximate this in various languages - you *can*
> build concrete instances of abstract base classes (i.e. ones with all
> virtual methods) in C++ at runtime if you don't mind a bit of
> bit-bashing; but you can't build a struct, or class which is used as a
> value (i.e. not passed around as a pointer) which existing compiled code
> can used.
>
> Warmest Regards,
>
> Mark.
>
> P.S. Looking at this another way - I'd perhaps characterize the above as
> arrays are not 'complete' as values in LiveCode (as in: you can't use
> arrays in all places where you can use strings, and would still make
> sense), but I would say they were 'first-class'. I'd suggest
> 'completeness as values' is a more stringent requirement than
> 'first-class' - and is more that 'code has not been written to do that'
> (incomplete), rather than the 'model of the language disallows any
> notion of it being possible' (not first-class).
>
> P.P.S. You could rewrite your example as:
>      set the beautiful_Colour [ the arrayEncode of spellingArray ] of
> this card to "light-grey"
> Which suggests that arrays are actually 'complete' in LiveCode in the
> sense suggested above - it is just you (as the coder) have to work a bit
> harder to use them as such.
>
> --
> Mark Waddingham ~ mark at livecode.com ~ http://www.livecode.com/
> LiveCode: Everyone can create apps
>
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