Modify for postgres specific variable expansion

[qjhart]

You example was incredibly clarifying. Looking at that, I have an alternative suggestion. Postgres has variable expansion, which is in some ways clunky, but in other ways super nice. One part of this is that it will do shell command substitution, which we can use to simplify the setup.

Taking your example, we replace with: (This is not fully baked)

\set require `pwd` / foo.js
\set  es6-to-plv8  'es6-to-plv8 -h '  :require 
\set browserified :`es6-to-plv8`

create or replace function init() returns void
language plv8
as $function#
:browserified
$function$;

create or replace function foo()
returns text
language plv8 IMMUTABLE STRICT
as
$$
return Testing.foo();
$$;