Adding pllua (Lua PostgreSQL Procedural Language) type annotations.

[fcr--]

Since pllua (Procedural Language Lua) is supposed to run inside PostgreSQL (as functions, procedures or in do blocks), it isn't distributed as a luarocks package, instead it is distributed with PostgreSQL itself. That said, it still makes sense to have type annotations for it.

Note: most comments (and field names) were copied from the pllua's documentation.

[fcr--]

Just to be consistent with check-all.sh, and btw, /bin/sh sometimes points to other shells like dash, where BASH_SOURCE is not defined.

[fcr--]

Is there any way to "re-export" a module or a bunch of symbols? At least being able to do something like:

local elog = require 'pllua.elog'
[...]
   elog: typeof(elog.elog)
   debug: typeof(elog.debug)
   log: typeof(elog.log)
   info: typeof(elog.info)
   notice: typeof(elog.notice)
   warning: typeof(elog.warning)
   error: typeof(elog.error)

Something like typeof would also be helpful for referencing local types that could not be exported.

[hishamhm]

The nested type should be publicly accessible just like the record attributes, so you should be able to use elog.ELogInfo from client code that requires this module.

[fcr--]

Yes, elog.ELogInfo is being exported (and it's being used in spi.d.tl), however I meant being able to express a "poly" type and associate that to a type variable, something like type logfunction = function(message: string) & function(sqlstate: string, message: string) & ... but I guess we first would need some syntax to express type intersection.

[hishamhm]

Merged, thank you!