This note is in Hasura.Backends.Postgres.SQL.Types.
In order to better be able to reason about values representing SQL binders and variables we are in the process of retiring the generic ‘Identifier’ type in favor of the more specific types ‘TableIdentifier’ and ‘ColumnIdentifier’.
Likewise, we distinguish binders of names from uses of names: The types
‘TableAlias’ and ColumnAlias are used to for binders, whereas
TableIdentifier and ColumnIdentifier represent usages or references of
previously bound names.
We want to ensure these are handled in an hygenic way: * ‘TableAlias’es and ‘ColumnAlias’es can be constructed freely, but * ‘TableIdentifier’ can only be constructed from a ‘TableAlias’ via ‘tableAliasToIdentifier’, and * ‘ColumnIdentifier’s can only be constructed from a ‘ColumnAlias’, and potentially be qualified with a ‘TableIdentifier’.