[RFC] Operators GET, SET and CLEAR for L bits

[Mohammad-Reza Nabipoor]

Hi Jose.

On Wed, Jan 28, 2026 at 11:48:18AM +0100, Jose E. Marchesi wrote:
> 
> > Hello people!
> >
> > I propose to add the following operators (to apply to L bits) to the
> > extended standard prelude:
> >
> >
> >   prio SET = 7, CLEAR = 7;
> >
> >   op SET = (bits b, int n) bits:
> >      if n >= 1 AND n <= bits_width
> >      then b OR 2r1 SHL (n-1)
> >      else b
> >      fi;
> >
> >   op CLEAR = (bits b, int n) bits:
> >      if n >= 1 AND n <= bits_width
> >      then b AND NOT (2r1 SHL (n-1))
> >      fi;
> >



I like the idea of SET and CLEAR dyadic operators!



> >   prio GET = 4;
> >
> >   op GET = (bits b, int n) bool:
> >      if n >= 1 AND n <= bits_width
> >      then ABS (b AND n) /= 0
> >      fi;
> 
> Note GET is not needed, because the standard operator ELEM does exactly
> that:
> 
>    flags ELEM flag_with
> 


Cool!


> 
> but it counts from the left! i.e. it gives you the boolean corresponding
> to the ith boolean starting from the left :)


Yeah! Casting to []bool is also does that. Unfortunately (esp. for me) RR authors
were big-endian people :(


> 
> Also I now realize we still have to implement the bitspack standard
> procedures..
> 

Good outcome!