Protocols and operators mostly

orchid-extension/src/func_atom.rs

@@ -31,6 +31,19 @@ trait_set! {
 	trait FunCB = Fn(Vec<Expr>) -> LocalBoxFuture<'static, OrcRes<GExpr>> + 'static;
 }
 
+task_local! {
+	static ARGV: Vec<Expr>;
+}
+
+pub fn get_arg(idx: usize) -> Expr {
+	ARGV
+		.try_with(|argv| {
+			(argv.get(idx).cloned())
+				.unwrap_or_else(|| panic!("Cannot read argument ##{idx}, only have {}", argv.len()))
+		})
+		.expect("get_arg called outside ExprFunc")
+}
+
 pub trait ExprFunc<I, O>: Clone + 'static {
 	fn argtyps() -> &'static [TypeId];
 	fn apply<'a>(&self, hand: ExecHandle<'a>, v: Vec<Expr>) -> impl Future<Output = OrcRes<GExpr>>;