[Oberon] Easter eggs in Oberon

Joerg joerg.straube at iaeth.ch
Mon Apr 13 21:19:46 CEST 2020


Where is defined what the operator / shall do?
I mean who does forbid me to state / is equal to DIV if both operands are INTEGER.


> Am 13.04.2020 um 20:49 schrieb August Karlstrom <fusionfile at gmail.com>:
> On 2020-04-13 17:36, Joerg wrote:
>> The word „numeric type“ is not clearly defined in the report.
>> Eg. is BYTE part of the numeric types?
> BYTE is defined as "the integers between 0 and 255" and integers are numeric, so the answer must be yes.
>> Or is INTEGER part of the numeric type?
> It has to be, otherwise you would not able to calculate anything with integers.
>> If it was you sould be able to write i := i / 3;  (as / is defined on numeric types)...
> No, because "The operators +, −, *, and / apply to operands of numeric types. Both operands must be of the same type, which is also the type of the result." The result of i / 3 is not an integer unless i is a multiple of three. Therefor it applies to operands of type REAL.
>> The Oberon report leaves some room for interpretation... (especially for corner cases)
>> b := -2;  is equivalent to b := 254;
> It may give the same result on one implementation but it is still undefined; again the Oberon report says that BYTE is "the integers between 0 and 255," not "the integers between -128 and 127."
> -- August
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