Ships fn print : forall a. Show a => (a borrow) -> () !IO in the
prelude with explicit-let body \\x -> let s = show x in do
io/print_str s. Three new E2E fixtures + tests verify the full
path:
- show_print_smoke: 4 primitives smoke (print 42 / true / 'hello' /
3.14) — compile, run, expected stdout
- show_user_adt: data IntBox + instance prelude.Show IntBox +
print (MkIntBox 7) — stdout '7'
- show_no_instance: let f : Int -> Int = \\x -> x in do print f —
fires Show-aware NoInstance with DESIGN.md §Prelude(built-in)
classes cross-reference
IR-shape pin in print_mono_body_shape.rs asserts post-mono
print__Int.body is structurally Term::Let → App(show__Int) →
Do(io/print_str). Protects the explicit let-binder for the heap-Str
RC discipline per eob.1 Str carve-out.
Three plan-defects-fixed-inline surfaced during user-ADT E2E,
necessary repairs to make the spec's stated user-ADT trajectory
work end-to-end:
(a) mono.rs (2 sites): MonoTarget::FreeFn::type_args were carrying
bare type-cons references; normalised to canonical
<owner>.<bare> form via workspace_registry.normalize_type_for_lookup
so synthesised cross-module bodies' post-mono walks reach the
registry-keyed instance entries. Symmetric to the existing
class-method-arm normalisation.
(b) codegen/lib.rs (3 sites: resolve_top_level_fn, lower_app
cross-module arm, synth_with_extras Var arm): post-mono
synthesised bodies may carry cross-module references to modules
their source template didn't import (prelude.print__<UserType>
references show_user_adt.show__<UserType> even though prelude
does not import user modules). Fall back to direct
module_user_fns lookup when prefix not in import_map. Both
ends were independently typechecked before mono ran; the
cross-module ref is created by mono not by source.
(c) lib.rs synth FreeFnCall arm: walked Type::Forall.constraints,
substituted rigid vars with fresh metavars, pushed one
ResidualConstraint per declared constraint. Without this,
print f at Int -> Int would silently typecheck and fail with
a confusing 'unknown variable: show' at codegen rather than
fire the right typecheck-time NoInstance diagnostic.
NoInstance Float-aware arm in check/lib.rs:770-779 extended with
a parallel class == 'prelude.Show' branch that cross-references
DESIGN.md §Prelude(built-in) classes verbatim. Negative-fixture
test asserts code 'no-instance' + Show substring + Prelude-(built-in)-
classes substring.
DESIGN.md §Prelude(built-in) classes milestone-24 paragraph flips
fn print from 'ships in 24.3' to 'shipped in iter 24.3' with body
shape + pin file reference. §Float semantics gains a Show-Float
NaN-spelling cross-reference paragraph linking show 1.5 / show nan /
show inf to instance Show Float via float_to_str.
Roadmap P1 'Post-22 Prelude — Show + print rewire' flipped to [x]
with closing summary naming all three shipped iters (24.1 / 24.2 /
24.3). New P2 entry 'Retire io/print_int|bool|float effect-ops +
migrate example corpus to print' inserted at top of P2.
Tests: 556 passed (was 552 + 4 new). bench/cross_lang exit 0;
bench/compile_check + bench/check exit 1 on documented noise-class
metrics per the audit-cma lineage envelope (8th consecutive
audit-grade observation, baseline pristine per conservative-call).
Milestone 24 closes structurally with this iter. Standard audit
pipeline next.
Brummel
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