Extends parseParams in src/parser.zig:1558 to recognize a leading
`..` before the optional `$` sigil and the parameter name. The
old `args: ..T` form (variadic marker after the colon) still
works — both paths set the same `is_variadic` flag.
A pack declaration `..$args` parses as:
- `is_variadic = true` (from the leading `..`)
- `is_comptime = true` (from the `$` sigil)
- `type_expr = inferred_type` (no `:` annotation)
The no-colon branch now propagates `is_variadic` and `is_comptime`
onto the Param struct so later slices (type rep, impl matching,
monomorphisation) can read both flags from the parsed AST without
re-deriving from token sequence.
`examples/150-pack-parse.sx` flips from rejecting-with-error to
positive parse smoke. No semantic effect yet — `foo` is declared
but never instantiated.
191/191 example tests + `zig build test` green.
First slice of the `..$args` (variadic heterogeneous type pack)
feature. Locks in the current parser-rejection behavior so the
next commit's parser extension shows up as a behavior shift.
`examples/150-pack-parse.sx` declares `foo :: (..$args) -> s64`.
Today's parser hits `..` where it expects a parameter name
(parseParams in src/parser.zig:1558 only handles `..` inside the
type position after a colon) and emits "expected parameter name".
Expected output captures this rejection.
Per FFI cadence rule, this is the "test fails today, passes after
next commit's parser change" pair.
Pack feature plan saved at
~/.claude/plans/lets-see-options-for-merry-dijkstra.md ("Variadic
heterogeneous type packs" section). Motivates replacing the
hand-rolled per-signature `Into(Block)` impls with one generic
`impl Into(Block) for Closure(..$args) -> $R`; also unlocks
compile-time arity/type errors for `print`/`format`.
191/191 example tests + `zig build test` green.
