wasm: Get List.map2 working

compiler/mono/src/code_gen_help/mod.rs

@@ -25,7 +25,7 @@ const ARG_2: Symbol = Symbol::ARG_2;
 pub const REFCOUNT_MAX: usize = 0;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
-enum HelperOp {
+pub enum HelperOp {
     Inc,
     Dec,
     DecRef(JoinPointId),
@@ -185,16 +185,16 @@ impl<'a> CodeGenHelp<'a> {
     /// Generate a refcount increment procedure, *without* a Call expression.
     /// *This method should be rarely used* - only when the proc is to be called from Zig.
     /// Otherwise you want to generate the Proc and the Call together, using another method.
-    /// This only supports the 'inc' operation, as it's the only real use case we have.
-    pub fn gen_refcount_inc_proc(
+    pub fn gen_refcount_proc(
         &mut self,
         ident_ids: &mut IdentIds,
         layout: Layout<'a>,
+        op: HelperOp,
     ) -> (Symbol, Vec<'a, (Symbol, ProcLayout<'a>)>) {
         let mut ctx = Context {
             new_linker_data: Vec::new_in(self.arena),
             recursive_union: None,
-            op: HelperOp::Inc,
+            op,
         };
 
         let proc_name = self.find_or_create_proc(ident_ids, &mut ctx, layout);