Re: [RFC] Changing the unit of an offset

[Bruno Haible]

Hi José,

> But that gives us a magnitude, not an offset.  It would of course be
> possible to write:
> 
>   (poke) (anoffset/#B)#B
>   16#B
> 
> But that is too cumbersome.
> 
> So, what about having some short convenient syntax to change the unit of
> an offset?
>
> Note we would need to variants.  One equivalent to
> 
>   (offset/#UNIT)#UNIT
> 
> And the other equivalent to
> 
>   (offset/^#UNIT)#UNIT
> 
> The first uses truncating division, the second ceiling division.
> 
> Anybody has any suggestion for the syntax?

First, note that it's more than "changing the unit", because — as you say —
it may lose some bits.

I therefore dislike an attribute-like syntax

    offset'floor_as(#UNIT)
and offset'ceil_as(#UNIT)

and instead prefer see a syntax like the one used for casts:

    offset floor_as #UNIT
and offset ceil_as #UNIT

or — if you can accommodate 3-character operators in the lexer —

    offset /_* #UNIT
and offset /^* UNIT

Note that the latter is confusing, because /* is not an operator.

Bruno