Reference column alias for common expressions

[Wood May]

Hi,
    Some databases (like Teradata) support the following syntax:

    select col1, col2*20 as col2_1, col2_1*200 as col3_1 from your_table;

    The last element in the target list can refer the second one using its 
alias.

    This feature is similar to some programming languages (like Lisp)'s let*​.

    For Postgres, it seems the only way is to write a subquery and then a new 
target list.

    Will Postgres plan to support this feature?

    Thanks a lot!