[Grace-core] Draft Minutes of Teleconference 9-10.2.2014

[Kim Bruce]

My text books from the "olden" days when we talk Pascal don't seem to allow initializing variables in declarations, though some newer implementations apparently do with the "value" key word.

I would think it would be very confusing to students to write
   var x = 10 
   x := x + 1

I think of 
    var x := 10
as an abbreviation for 
    var x
    x:= 10


Kim



> On Feb 12, 2015, at 11:00 AM, James Noble <kjx at ecs.vuw.ac.nz> wrote:
> 
>> A brief comment:
> 
> :-)
> 
>> I agree that it is confusing at first remembering the difference between = and := given our conditioning with C/C++/Java.
> 
> actually I keep it straight most of the time - probably 'cos I started with BASIC then Pascal
> 
>> I find it useful to have an asymmetric symbol used for assignment as novices often have trouble remembering the direction of assignments. (They still get confused with :=, but a bit less in my experience).  
> 
> ChucK goes consistently right-to-left and so writes 7 => x 
> 
>> I also think it is useful to distinguish between definitions and assignments as they are quite distinct operations.  I had earlier suggested using "is" for constant definitions, but there seemed to be no enthusiasm for that.
> 
> so do I.
> 
> I'm concerned about the syntactic inconsistency between "def" and "var" declarations only;
> this is what trips me up. 
> 
> all I was wondering about was changing
> 
> var x := 7  
> 
> to 
> 
> var x = 7
> 
> in other words
> = used only in declarations - and in all in declarations & initialisations
> == used for comparison
> := used for assignment (only to change things, not to set up initial values) 
> 
> 
> this is pretty much where Pascal ended up 
> 
>> I had earlier suggested using "is" for constant definitions, but there seemed to be no enthusiasm for that.
> 
> not given how we're using "is" for annotations. 
> Standard Pascal uses "value" apparently - not that I remember it - 
> but most implementations either also support "=" or only "=" and not "value" 
> 
> J