feat: support boolean conditional expressions

source/sema/check/check.hon

@@ -1615,6 +1615,14 @@ demand proc(state @mut State, id ast.NodeId, expected Type, code diagnostics.Cod
             return
         }
     }
+    if (state.cells[usize(id)].role == .expression and ast.expr_kind(state.tree, id) == .match_expr) {
+        state.cells[index].expected = expected
+        for 0..ast.match_arm_count(state.tree, id) |i| {
+            arm :: ast.match_arm_view(state.tree, ast.match_arm(state.tree, id, i))
+            if (arm.expression) try demand(state, arm.body, expected, code)
+        }
+        return
+    }
     if (expected.kind == .fallible) {
         descriptor :: state.arrays.items[usize(expected.array_type)]
         actual := group_type(state, id)
@@ -1691,14 +1699,6 @@ demand proc(state @mut State, id ast.NodeId, expected Type, code diagnostics.Cod
             state.pointers.items[usize(expected.pointer_type)].element, code)
         return
     }
-    if (state.cells[usize(id)].role == .expression and ast.expr_kind(state.tree, id) == .match_expr) {
-        state.cells[index].expected = expected
-        for 0..ast.match_arm_count(state.tree, id) |i| {
-            arm :: ast.match_arm_view(state.tree, ast.match_arm(state.tree, id, i))
-            if (arm.expression) try demand(state, arm.body, expected, code)
-        }
-        return
-    }
     literal_node :: state.cells[index].literal
     if (
         expected.nominal != ast.NodeId(maxval!(u32))

source/sema/specialize/specialize.hon

@@ -4349,6 +4349,18 @@ expression_type proc(state @mut State, id ast.NodeId, depth usize) ast.NodeId !
         .literal_bool: return try builtin(state, id, .bool)
         .literal_string: return try builtin(state, id, .string)
         .literal_void: return try builtin(state, id, .void)
+        .match_expr: {
+            result := no_node
+            for (0..ast.match_arm_count(&state.tree, id)) |i| {
+                arm :: ast.match_arm_view(&state.tree, ast.match_arm(&state.tree, id, i))
+                if (!arm.expression) return no_node
+                annotation :: try expression_type(state, arm.body, depth + 1)
+                if (annotation == no_node) continue
+                result = annotation
+                if (!flexible(state, arm.body)) return result
+            }
+            return result
+        }
         .builtin_call: {
             name :: ast.literal_text(&state.tree, ast.builtin_call(&state.tree, id).name)
             count :: ast.call_arg_count(&state.tree, id)