iter 22b.3.1: mono pass skeleton — identity for class-free workspaces

crates/ail/src/main.rs

@@ -2032,6 +2032,13 @@ fn build_to(
         // load-time remains valid.
         registry: ws.registry.clone(),
     };
+    // Iter 22b.3: monomorphisation pass. After `lift_letrecs` and
+    // before codegen, every (class-method, concrete-type) call-site
+    // pair becomes a synthesised top-level fn; user call sites are
+    // rewritten to target those names. Class-free workspaces flow
+    // through bit-identically; see `ailang_check::monomorphise_workspace`.
+    let ws = ailang_check::monomorphise_workspace(&ws)
+        .map_err(|e| anyhow::anyhow!("monomorphise_workspace: {e}"))?;
     let ir = ailang_codegen::lower_workspace_with_alloc(&ws, alloc)?;
     let tmpdir = std::env::temp_dir().join(format!("ailang-{}", std::process::id()));
     std::fs::create_dir_all(&tmpdir)?;

crates/ail/tests/typeclass_22b3.rs

@@ -0,0 +1,49 @@
+//! Iter 22b.3: monomorphisation pass tests.
+//!
+//! Co-located with `typeclass_22b2.rs` so the typeclass-feature
+//! coverage is browsable in one directory. Tests use the same
+//! `examples_dir()` pattern — `cargo test`-cwd is the crate dir,
+//! the fixtures live in `<repo>/examples/`.
+
+use std::path::PathBuf;
+
+fn examples_dir() -> PathBuf {
+    // crates/ail/ → repo root → examples/
+    let mut d = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
+    d.pop();
+    d.pop();
+    d.join("examples")
+}
+
+#[test]
+fn monomorphise_workspace_is_identity_on_class_free_workspace() {
+    // Pick any class-free fixture; `examples/hello.ail.json` is
+    // the canonical class-free smoke test.
+    let entry = examples_dir().join("hello.ail.json");
+    let ws = ailang_core::load_workspace(&entry).expect("load");
+    let diags = ailang_check::check_workspace(&ws);
+    assert!(diags.is_empty(), "fixture must typecheck: {:?}", diags);
+
+    let ws = ailang_check::monomorphise_workspace(&ws)
+        .expect("mono on class-free workspace");
+
+    // Module set unchanged.
+    let before = ailang_core::load_workspace(&examples_dir().join("hello.ail.json"))
+        .expect("re-load");
+    assert_eq!(
+        ws.modules.keys().collect::<Vec<_>>(),
+        before.modules.keys().collect::<Vec<_>>(),
+        "module set must be identical"
+    );
+    // Per-module def list unchanged (compare by canonical-JSON hash).
+    for (mname, m) in &ws.modules {
+        let before_m = &before.modules[mname];
+        let h_after = ailang_core::module_hash(m);
+        let h_before = ailang_core::module_hash(before_m);
+        assert_eq!(
+            h_after, h_before,
+            "class-free module `{}` must hash-identical through mono",
+            mname
+        );
+    }
+}