'interval' column type is not supported

[pawurb]

Hi. It looks like the lib does not support 'interval' column type. Sample query:

select interval '1 minute';

Would it be possible to include it? I'm just getting started with Haskell but maybe NominalDiffTime could work here?

[roelvandijk]

See lpsmith/postgresql-simple#176 for a discussion about FromField NominalDiffTime.
In short: PostgreSQL interval can include months. You can't correctly convert months to days without context.

See lpsmith/postgresql-simple#219 for a Haskell type which exactly matches a PostgreSQL interval.

[phadej]

See #60