Clarification needed for `let()` function behaviour and sub-expressions about jmespath.spec HOT 1 CLOSED

Here are some pointers for discussion.

I think the main – if not only – source of confusion comes from the arguably counter-intuitive behaviour when evaluating the RHS of a sub-expression. In that case, I would be happy to close that source of confusion. This would be quite easy (I think) to implement, as each new sub-expression would create a new fresh scope chain.

Here is how it could be implemented:

    case parsing.ASTSubexpression:
      left, err := intr.Execute(node.Children[0], value)
      if err != nil {
        return nil, err
      }
      if left == nil {
        return nil, nil
      }
-    return intr.Execute(node.Children[1], left)
+    return intr.WithScope(nil).Execute(node.Children[1], left)

from jmespath.spec.