-### Expression list
-
-We take a brief detour, now that we have expressions, to describe lists
-of expressions. These will be needed for function parameters and
-possibly other situations. They seem generic enough to introduce here
-to be used elsewhere.
-
-And ExpressionList will use the `List` type of `binode`, building up at
-the end. And place where they are used will probably call
-`reorder_bilist()` to get a more normal first/next arrangement.
-
-###### declare terminals
- $TERM ,
-
-`List` execs have no implicit semantics, so they are never propagated or
-interpreted. The can be printed as a comma separate list, which is how
-they are parsed. Note they are also used for function formal parameter
-lists. In that case a separate function is used to print them.
-
-###### print binode cases
- case List:
- while (b) {
- printf(" ");
- print_exec(b->left, -1, bracket);
- if (b->right)
- printf(",");
- b = cast(binode, b->right);
- }
- break;
-
-###### propagate binode cases
- case List: abort(); // NOTEST
-###### interp binode cases
- case List: abort(); // NOTEST
-
-###### Grammar
-
- $*binode
- ExpressionList -> ExpressionList , Expression ${
- $0 = new(binode);
- $0->op = List;
- $0->left = $<1;
- $0->right = $<3;
- }$
- | Expression ${
- $0 = new(binode);
- $0->op = List;
- $0->left = NULL;
- $0->right = $<1;
- }$
-