Re: [9fans] sam command language

[Rob Pike <rob@mightycheese.com>]

> for instance, suppose i've got a little sam expression that nicely
> isolates particular subregions of text.  i can't work out a way to
> match only characters which appear at the very beginning (or end) of
> "dot".  kind of similar to ^ and $ except with respect to the
> boundaries of the current selection.

long ago, i considered making ^ and $ mean this in sam.  they clearly
need to mean beginning and end of line at the top level, but when we
x down, maybe they should mean beginning and end of the substring.
i think i even tried to implement it.  in any case, i decided against
it; i
think it was a combination of not liking the shift in meaning and the
fact
that ^ and $ meaning bol and eol at the top level meant that they
required
special handling already, since sam really doesn't know much about
lines, unlike ed.  if the whole file is just one long string, which is
exactly
how sam works, shouldn't ^ and $ then mean beginning of file and end
of file?  that's not very useful.

and then, in the end, i felt the need for the modified version of ^ and
$
so rarely that i don't really mind not having them. unlike in the modern
world, back then adding a feature was considered something to consider
carefully, rather than just adding it in case someone might conceivably
want it one day.

-rob