read-only and write-only params

8.14: adda/cstr/function/syntax/read-only and write-only params:
 if a parameter gets a pointer, (eg, /.int)
then it can be modifying both the pointer and the int,
so, shouldn't we have a syntax for expressing
what the algorithm intends to do with both?
. so, we still need a syntax for what is read-only .
. if a parameter expects a read-only,
then we can give it a modifiable
while expecting that it won't modify it .
. how about syntax for write-only?
maybe we should use (.typemark^) for that?
. the latest idea obviates a read-only syntax:
(inout param's)`f(x) -- in that example,
the x param is in-mode only (read-only)
that includes both the pointer and its target .
. notice that if the input is shared by any co.programs,
then we need to lock it as read-only or copy it,
unless we expect it to rely on the interactive value .]