Aggregate min on Bool column generates invalid query

[ryskajakub]

Running Aggregate.min function on boolean column generates an invalid query that will fail when ran.

select id, min(closed) from
No function matches the given name and argument types. You might need to add explicit type casts.

Some other functions from the same module might have the same problem, like avg for string fields etc.

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Idea: It could be solved by restricting the a type of min with a methodless typeclass. All the datatypes that can be applied to the function would be instances of the typeclass.

[tomjaguarpaw]

You are correct. This is currently a hole in Opaleye's "type system". You will notice there is a similar problem for the ordering operators, (>), (>=) etc.. Your suggested fix is sensible I think.

[tomjaguarpaw]

be092f3