c792642d76
Step 4A final slice's lock-in. `$args` (whole pack) as a bare
expression should evaluate to a comptime `[]Type` slice value
— the whole pack passed through as data so builder fns can
walk it.
Today's parser arm (commit fd03b58, M5.A.next.4.3) requires
the `[<int_literal>]` form: bare `$<pack_name>` hits the
focused "expected '[' after '$<pack_name>'" diagnostic I added
when wiring the indexed access.
`examples/170-pack-bare-value.sx` exercises four call shapes
of a pack-fn whose body binds `list := $args` then returns
`list.len`. Expected output (post-fix) is "0/1/3/4" per call.
Today the parser rejection diff makes the test fail —
209/209 + 1 expected-failing = 210 total.
Cadence shape 2: expected output is the WORKING shape; pre-fix
the parser-error diff fails. Next commit lands the parser
extension + AST node + lowering and the test flips green.
36 lines
1.3 KiB
Plaintext
36 lines
1.3 KiB
Plaintext
// Variadic heterogeneous type packs — step 4 final slice (4A
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// bare): `$args` referenced bare (without `[...]` indexing) in
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// expression position should evaluate to a comptime `[]Type`
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// slice value — the whole pack passed through as data so
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// builder fns can walk it.
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//
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// Use case (eventual): step 5's generic Into(Block) impl body
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// convert :: (self: Closure(..$args) -> $R) -> Block {
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// #insert build_block_convert($args, $R);
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// }
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// where `build_block_convert(args: []Type, ret: Type) -> string`
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// is a regular sx fn the interp executes — it walks `args` to
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// emit a trampoline fn matching the per-mono signature.
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//
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// Today the parser-arm I wrote for `$<ident>[<int>]` (commit
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// fd03b58, M5.A.next.4.3) REQUIRES the `[` after the pack
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// name; bare `$args` hits a focused diagnostic. This file
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// pins that rejection. Next commit makes the `[` optional —
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// no `[` yields a `comptime_pack_ref` AST node which lowering
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// converts to a `[N x Type]` aggregate of `const_type` values.
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#import "modules/std.sx";
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len_of :: (..$args) -> s64 {
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list := $args;
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return list.len;
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}
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main :: () -> s32 {
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print("{}\n", len_of());
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print("{}\n", len_of(42));
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print("{}\n", len_of(1, 2, 3));
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print("{}\n", len_of("a", true, 3.14, "b"));
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return 0;
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}
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