C-u before an eval marks a form so the program stops when it runs
(DISCUSS.md 9). The mark arrives as a position in a separate :pause field
and is applied to the Ast after parsing: splicing text into the source
would move every line and column after it, and the error overlays, the
layout, the break loop's frame locations and DWARF all read those.
Ast.mark_pause puts a (pause) call at whatever starts at that position --
wrapping a sub-expression in a do, or going to the front of a defn's body,
since a declaration cannot be wrapped. A position that matches nothing is
refused rather than installed unmarked, which would report a breakpoint
that is not there.
It sticks with no extra state: the marked declaration is what goes into
the session, so an ordinary C-c C-c over the same form clears it.
The daemon half only; the Emacs command and its overlay are not built.
HANDOFF-f2.md has the rest, in order.
Joseph Ferano
6f8a7300d5