Hi Daniel,

Thanks for the code. However, :coerce is already there, named :type,
and the way to-sql-string is currently used, it should A) not use
S-SQL functions, since cl-postgres does not depend on S-SQL, and B)
serialise to a format that can also be used to pass parameters to
prepared queries. I'm not that knowledgeable about Postgres' textual
formats, but it appears that a value like ARRAY[1, 2, 3] can not be
written as a parameter:

   Database error 22P02: array value must start with "{" or dimension
information