Astrobe Forum

Hello,
This series of enhancement topics you started recently is really usefull

It would be nice to have some examples showing the use of SET operators in expressions and as single operands
eg:
u:= s- {8,9,13} if s:={7,9,14}
u:= -s

not so clear for me the use of IS an the TYPE "Tree"
Regards

Alain

Thank you for your feedback - much appreciated. There's a lot more to come if there is sufficient interest

Niklaus Wirth has written a paper on the use of SETs titled "SET: A neglected data type and its compilation for the ARM". You can download a copy from:

https://people.inf.ethz.ch/~wirth/Oberon/SETs.pdf

When you subtract one set from another, any element that is common to both sets is removed. No other element is affected.

Thus, if you execute the code: then u = {7, 14};

-SET is the complement of a set. i.e. the resulting set contains all the elements that were not in the original set and none of the elements that were in the original set.

If s = {7, 9, 14} then -s = {0,1,2,3,4,5,6,8,10,11,12,13,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31}

This is more conveniently written as {0..6, 8, 10..13, 15..31}