--- a/src/func.h	Mon Aug 26 08:40:28 2019 +0200
+++ b/src/func.h	Mon Aug 26 08:45:27 2019 +0200
@@ -13,6 +13,16 @@
  * @{
  */
 
+/// Descriptor of a function argument.
+typedef struct {
+    /// Name of the argument. Useful for debugging.
+    ystr_t argname;
+    /// Reference (usually anonymous/numeric) to the value slot of this
+    /// argument. It is created during the compile stage, and will be used
+    /// during execution.
+    yref_t argref;
+} yarg_desc_t;
+
 /**
  * @brief Compiled function code. Functions are usually inserted in the global
  * value table and referenced there.
@@ -20,13 +30,15 @@
  * TODO: Extend to allow reference capture for closures?
  */
 typedef struct {
-    /// Name of a function.
+    /// Expressions making up the function. Often a list; the value of the last
+    /// expression is the value of the invoked function. `args` describes the
+    /// references in `body` that are to be bound before calling.
+    yexpr_t body;
+    /// Name of the function.
     ystr_t name;
-    /// How many arguments it expects.
-    size_t nargs;
-    /// Expressions making up the function. Often a list; the value of the last
-    //expression is the value of the invoked function.
-    yexpr_t body;
+    /// Vector of yarg_desc_t values, each describing an argument, in order of
+    /// appearance.
+    yvec_t args;
 } yfunc_t;
 
 /**