Saying "the fields are not available" was under-claiming. A condition is a
struct, and Tast.structs holds every struct's field names and types in the
daemon, which owns the build — no running program is involved in answering
what a Missing is made of. Only the values need the pointer the break loop
was handed, and break_loop currently discards that pointer, so they are two
different gaps with two different fixes on two different sides of the socket.
The buffer now draws a field named and typed with its value refused, which is
what tells you whether the field you were about to blame is even a field of
this condition.
Navigation backwards was not the same list walked the other way. Forward
wrapped and backward stopped, and from the middle of a line the two disagreed
about where a field begins — a field line carries the property on all of it,
so a property-change walk from mid-line finds the end of the field you are
already in. Both now go through one list of field starts. The mid-line case
went red on the first try and the expectation was the thing that was wrong:
landing on the current field's start is what CIDER does and is the less
surprising of the two.
C-x C-e renders once and stops at depth 4 and span 8. A field past either
comes back as "..." and nothing recovers it from the echo area. Re-rooting
the walk at that field renders it from depth 0, so the bound moves with you
— that, and not tidiness, is why an inspector is worth having beside the
expression evaluator.
CIDER keeps its inspector stack on the server because a JVM value can be
retained. Nothing here can: a Flan value has no header and the thunk that
rendered it is dlclosed the moment it returns. So the stack is a stack of
expressions on this side, and going into a field means sending a different
one — (.pos b) where the last one was b. It costs a re-evaluation per step,
which buys a view that is never stale and is why refresh is a key someone
presses rather than a timer.
Driven from fixtures, which is also the only way the cases a live program
will not hold still for get tested at all.
