Generalize TermDef for multiple parameter lists

The member `params` is renamed to `paramLists` to reflect its new behavior. The type of `paramLists` is changed from `Opt[Ls[Tree]]` to `Ls[Tup]` to reflect its new behavior. It now returns a list of parameter tuples instead of a list of parameters.

hkmc2/shared/src/main/scala/hkmc2/syntax/Tree.scala

@@ -204,31 +204,33 @@ private def getName(t: Tree, symNme: Opt[Tree]): (Opt[Tree], Diagnostic \/ Ident
 
 trait TermDefImpl:
   this: TermDef =>
-  lazy val (symName, name, params, typeParams, signature): (Opt[Tree], Diagnostic \/ Ident, Opt[Ls[Tree]], Opt[Tree], Opt[Tree]) =
-    def rec(t: Tree, symName: Opt[Tree]):
-    (Opt[Tree], Diagnostic \/ Ident, Opt[Ls[Tree]], Opt[Tree], Opt[Tree]) =
-      t match
-      case InfixApp(id: Ident, Keyword.`:`, sign) =>
-        (symName, R(id), N, N, S(sign))
-      // show(t: Tree): Str
-      case InfixApp(App(id: Ident, args), Keyword.`:`, ret) =>
-        (symName, R(id), S(args :: Nil), N, N)
-      // show[A](t: Tree[A]): Str
-      case InfixApp(App(App(id: Ident, typeParams: TyTup), args), Keyword.`:`, ret) =>
-        // val sign = S(InfixApp(typeParams, Keyword.`->`, InfixApp(args, Keyword.`->`, ret)))
-        (symName, R(id), S(args :: Nil), S(typeParams), N)
+  lazy val (symName, name, paramLists, typeParams, signature): (Opt[Tree], Diagnostic \/ Ident, Ls[Tup], Opt[Tree], Opt[Tree]) =
+    def rec(t: Tree, symName: Opt[Tree]): (Opt[Tree], Diagnostic \/ Ident, Ls[Tup], Opt[Tree], Opt[Tree]) = t match
+      // fun f: Int
+      // fun f(n1: Int): Int
+      // fun f(n1: Int)(nn: Int): Int
+      case InfixApp(Apps(id: Ident, paramLists), Keyword.`:`, sign) =>
+        (symName, R(id), paramLists, N, S(sign))
+      // fun f[T]: Int
+      // fun f[T](n1: Int): Int
+      // fun f[T](n1: Int)(nn: Int): Int
+      case InfixApp(Apps(App(id: Ident, typeParams: TyTup), paramLists), Keyword.`:`, ret) =>
+        (symName, R(id), paramLists, S(typeParams), N)
+
       case InfixApp(Jux(lhs, rhs), Keyword.`:`, ret) =>
         rec(InfixApp(rhs, Keyword.`:`, ret), S(lhs))
-      case id: Ident =>
-        (symName, R(id), N, N, N)
-      case App(id: Ident, typeParams: TyTup) =>
-        (symName, R(id), N, S(typeParams), N)
-      case App(id: Ident, args) =>
-        (symName, R(id), S(args :: Nil), N, N)
-      case App(primary: App, second) =>
-        // TODO: handle the second parameter list
-        val (sn, id, first, tps, sig) = rec(primary, symName)
-        (sn, id, S(first.fold(Ls(second))(_ :+ second)), tps, sig)
+
+      // fun f
+      // fun f(n1: Int)
+      // fun f(n1: Int)(nn: Int)
+      case Apps(id: Ident, paramLists) =>
+        (symName, R(id), paramLists, N, N)
+      // fun f[T]
+      // fun f[T](n1: Int)
+      // fun f[T](n1: Int)(nn: Int)
+      case Apps(App(id: Ident, typeParams: TyTup), paramLists) =>
+        (symName, R(id), paramLists, S(typeParams), N)
+
       case Jux(lhs, rhs) => // happens in `fun (op) nme` form
         require(symName.isEmpty) // TOOD
         rec(rhs, S(lhs))