FOR IN {} suggestion for HP team

[Gilles]

It would be fine to have this kind of syntax with the Prime like in Mapple :

FOR n IN { } DO
END


For example :

FOR n IN {"Bleu" "Blanc" "Rouge"} Do
PRINT(n);
END

would result in

Bleu
Blanc
Rouge

This will allow things like

FOR n IN { 1 7 3 9 10 11 } DO ..

And why not { 3..10} to give easily {3 4 5 6 7 8 9 10}

[lenborje]

In programming languages that use a for-construct to do list processing, the list is often not modifiable during the loop. I usually need to add elements to the list during processing, and thus use the pattern below:


LOCAL lst = { ... whatever .. };
WHILE SIZE(lst) DO
LOCAL element=head(lst);
lst:=tail(lst);

...
END;

[Tim Wessman]

Why would anyone ever want a loop in a programming language that iterates over a fixed sized collection of some type of object? I can't imagine how that would be useful nor any language that has something similar...


/s

[Han]

(12-01-2014 03:54 PM)Tim Wessman Wrote:  Why would anyone ever want a loop in a programming language that iterates over a fixed sized collection of some type of object? I can't imagine how that would be useful nor any language that has something similar...

/s

I think the idea was not to actually loop over a fixed sized list, but to simply enable looping over lists so that one could do something like:

Code:


  FOR j IN mylist DO
    PRINT(j);
  END;

where mylist is created dynamically.

[ndzied1]

perhaps the /s means sarcasm off...

[parisse]

I agree with Han, iteration over a list is useful (it is the standard way to make loops in python by the way), and it is implemented in Xcas (with maple-like syntax).

[Gilles]

Python for example :

Code:


fruits = ['banana', 'apple',  'mango']
for fruit in fruits:       
   print 'Current fruit :', fruit

Or Mapple :

Code:


chiffres := {1, 2, 3, 4, 5, 6, 7, 8, 9}; 
for a in chiffres do 
for b in chiffres minus {a} do 
for c in chiffres minus {a, b} do 
 .
 .
 .
end do end do end do;

Or Ada, C, D, Delphi, Pascal, PHP,Perl , etc etc etc :
http://en.wikipedia.org/wiki/Foreach_loop

Of course the idea was not to be limited to fixed list...

[Han]

(12-01-2014 06:17 PM)ndzied1 Wrote:  perhaps the /s means sarcasm off...

Ha! It went completely over my head! <blush>