Cleaned up atoms

- Atoms now use MFBI to distinguish between thin and owned atoms.
- Introduced TryFromExpr and ToExpr (formerly ToClause) from the old FFI
- Standardized on Bottom being a ProjErr, which means that there will be no RTErr

orchid-extension/src/fun.rs

@@ -4,31 +4,34 @@ use dyn_clone::{clone_box, DynClone};
 use never::Never;
 use trait_set::trait_set;
 
-use crate::atom::{AtomCard, OwnedAtom};
-use crate::expr::{ExprHandle, GenClause};
+use crate::atom::Atomic;
+use crate::atom_owned::{OwnedAtom, OwnedVariant};
+use crate::expr::{ExprHandle, GenExpr};
 use crate::system::SysCtx;
+use crate::conv::{ToExpr, TryFromExpr};
 
 trait_set! {
-  trait FunCB = FnOnce(ExprHandle) -> GenClause + DynClone + Send + Sync + 'static;
+  trait FunCB = FnOnce(ExprHandle) -> GenExpr + DynClone + Send + Sync + 'static;
 }
 
 pub struct Fun(Box<dyn FunCB>);
 impl Fun {
-  pub fn new(f: impl FnOnce(ExprHandle) -> GenClause + Clone + Send + Sync + 'static) -> Self {
-    Self(Box::new(f))
+  pub fn new<I: TryFromExpr, O: ToExpr>(f: impl FnOnce(I) -> O + Clone + Send + Sync + 'static) -> Self {
+    Self(Box::new(|eh| I::try_from_expr(eh).map(f).to_expr()))
   }
 }
 impl Clone for Fun {
   fn clone(&self) -> Self { Self(clone_box(&*self.0)) }
 }
-impl AtomCard for Fun {
+impl Atomic for Fun {
   type Data = ();
   type Req = Never;
+  type Variant = OwnedVariant;
 }
 impl OwnedAtom for Fun {
   fn val(&self) -> Cow<'_, Self::Data> { Cow::Owned(()) }
-  fn call_ref(&self, arg: ExprHandle) -> GenClause { self.clone().call(arg) }
-  fn call(self, arg: ExprHandle) -> GenClause { (self.0)(arg) }
+  fn call_ref(&self, arg: ExprHandle) -> GenExpr { self.clone().call(arg) }
+  fn call(self, arg: ExprHandle) -> GenExpr { (self.0)(arg) }
   fn handle_req(&self, _ctx: SysCtx, req: Self::Req, _rep: &mut (impl std::io::Write + ?Sized)) {
     match req {}
   }