do: Elaborate on pattern syntax, add binary as operator

src/ast/macro_matcher.rs

@@ -193,6 +193,8 @@ impl<A: Annotation> Match<A> for Pat {
             (Pat::Slice(_), _) => false,
             (Pat::Alt(pat), Pat::Alt(expr)) => Match::recurse(sub, pat, expr),
             (Pat::Alt(_), _) => false,
+            (Pat::Typed(pat, _), Pat::Typed(expr, _)) => Match::recurse(sub, pat, expr),
+            (Pat::Typed(..), _) => false,
         }
     }
 
@@ -208,10 +210,24 @@ impl<A: Annotation> Match<A> for Pat {
             Pat::Tuple(pats) => pats.apply(sub),
             Pat::Slice(pats) => pats.apply(sub),
             Pat::Alt(pats) => pats.apply(sub),
+            Pat::Typed(pat, ty) => {
+                pat.apply(sub);
+                ty.apply(sub);
+            }
         }
     }
 }
 
+impl<A: Annotation> Match<A> for Ty {
+    fn apply(&mut self, sub: &Subst<A>) {
+        todo!("Apply subst {sub:?} for {self}.")
+    }
+
+    fn recurse(sub: &mut Subst<A>, pat: &Self, expr: &Self) -> bool {
+        todo!("Construct subst {sub:?} from {pat} and {expr}.")
+    }
+}
+
 impl<A: Annotation> Match<A> for Op {
     fn recurse(_: &mut Subst<A>, pat: &Self, expr: &Self) -> bool {
         pat == expr