From: bc@freeuk.com
On 28/11/2025 02:33, Janis Papanagnou wrote:
> On 11/27/25 18:59, bart wrote:
>> On 27/11/2025 17:38, Ike Naar wrote:
>>> On 2025-11-27, bart wrote:
>>>> Well, let's stick with C. Here are some features I use, and the C
>>>> equivalents (A has whatever type is needed):
>>>>
>>>> M C
>>>> -------------------------------------------------------------
>>>> [snip]
>>>> A.odd A & 1, or A % 1
>>>
>>> "A % 1" ?
>>
>> I guess A % 2 then.
>
> You guess? - LOL - okay. :-)
>
>> Note my remark about error proneness later on.
>
> Higher level abstractions (usually found in higher level languages)
> are always less error prone than low-level (or composed) constructs.
>
> "C" is inherently and by design a comparably low-level language, so
> I wonder what you complain here about. (You won't change that.)
So is mine. But it has many more 'commodity' features that make life
simpler. Plus a generally cleaner syntax to make it clearer.
> 'even' and 'odd' are higher level abstractions than bit-operations,
> and they are also _special cases_ (nonetheless useful; I like them,
> and I appreciate if they are present in any language). The general
> case of the terms like "odd" and "even" is defined mathematically,
> though;
The advantage of using '.odd' is that the language doesn't specify how
it works, just the behaviour.
(But internally, 'A.odd' is an alias for 'A.[0]', and 'A.even' is one
for 'not A.[0]', but with the extra proviso that these are read-only:
while `A.[0] := x' is possible, you can't do 'A.odd := x'.)
> so the natural way of describing them would (IMO) rather be
> based on 'x mod 2 = 1' and 'x mod 2 = 0' respectively. (So the "C"
> syntax with '%' is probably more "appropriate". Mileages may vary.)
I've made the mistake with % 1 more than once.
> You can of course add as many commodity features to "your language"
> as you like. I seem to recall that one of the design principles of
> "C" was to not add too many keywords. (Not sure whether 'A.odd' is
> a function or keyword above [in "your language"].)
It is a reserved word, which means it can't be used as either a
top-level user identifier, or a member name. With extra effort, it could
be used for both, but that needs some special syntax, such as Ada-style
"A'odd"; I've never got around to it.
In Pascal (where I copied it from) it is a reserved word.
> You made a mistake above (or just a typo), never mind. I suppose it
> stems from your primary "thinking in bits". - This is not meant to
> be offensive. - Back in university days (I still remember!) I made
> a similar typo but vice versa; I wanted to express "div 2" in some
> assembler language and accidentally wrote "shift-right 2", the same
> type of typo but the other way round. I *knew*, and didn't "guess",
> though, that "shift-right 1" would have been correct. ;-)
I use a decimal type in another language. There bitwise operations don't
work. I would have to define what they might do. For example, the
possibilities for `123 << 2` might be:
- Not valid (how it works now)
- 12300 (shift decimal digits)
- 492 (shift 'binary' digits)
That last simply defines as 'A << n' as meaning 'A * 2**n'.
> PS: BTW, I was always wondering why Pascal and Algol 68 supported
> 'odd' but not 'even'! - In the documents of the Genie compiler we
> can read: "This is a relic of times long past.", but beyond that
> it doesn't explain why it's a "relic". I can only guess that it's,
> as a special case, considered just unnecessary in the presence of
> the modulus operator.
Maybe because you can trivially define 'even' as 'not odd'.
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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