Close the coverage gap from attempt 1: example 0713 now builds integer
fields holding s64 MIN (-9223372036854775808) and s64 MAX
(9223372036854775807) — plus zero, a small negative, and a small positive —
and asserts the EXACT emitted bytes. This permanently pins the edge that
write_int is specifically engineered for (folding positives into negative
space so MIN's non-representable-positive magnitude serializes correctly).
s64 MIN is expressed as (0 - 9223372036854775807 - 1) because its magnitude
is not a representable positive s64 literal.
Test hygiene: stream to a repo-local, gitignored .sx-tmp/ path (created if
missing) instead of a fixed /tmp name, and unlink it right after read-back
so nothing leaks. Writer/model logic and src/ are untouched.
Add library/modules/std/json.sx — the JSON value model and writer
(reader lands in a later step).
Value model: a tagged union over null/bool/integer(s64)/string/array/
object. Objects are an ORDERED list of (key,value) pairs preserving
INSERTION ORDER (no hash map, never sorted/deduped). Integers only — no
fraction/exponent this milestone.
Heap discipline:
- Scalars carry no heap; string values are VIEWS into caller memory
(never copied into the node).
- Composite nodes (Array/Object) own growable child storage, allocated
through an EXPLICIT allocator parameter on the builder methods
(arr.add(v, alloc) / obj.put(key, val, alloc), mirroring List.append)
— never the implicit context allocator.
- The writer adds ZERO output allocations: it emits into a caller-
provided Sink, either a fixed []u8 buffer (overflow raises, never
truncates) or streaming straight to an fs.File through a small caller
staging buffer (no whole-document string; peak memory O(staging)).
Integer digits format in a stack [20]u8; s64 MIN is handled by
formatting in negative space. Sink/IO/overflow surface on the !
error channel.
examples/0713-modules-json-writer.sx builds a nested object + array +
string with every escape kind + negative int + bool + null, then asserts
the EXACT bytes (insertion order, escaping) from both the buffer sink and
the file-streaming sink, plus the overflow-raises path.
