In the Opaleye Tutorial, line 88 lists the following example ghci command.
ghci> printSql personQuery
personQuery there is a predefined query, and it appears that printSql is a function which prints the SQL generated by it.
Where is this printSql function defined? I have searched through all the modules of the opaleye package and do not see it defined there.
How can I see the SQL generated by an opaleye query?