title: Converting Postgres interval to Haskell NominalTimeDiff with postgresql-simple
body: <p>I (think I) need <a href="http://hackage.haskell.org/package/postgresql-simple/docs/Database-PostgreSQL-Simple-FromField.html#t:FromField" rel="nofollow">FromField</a> and <a href="http://hackage.haskell.org/package/postgresql-simple-0.4.10.0/docs/Database-PostgreSQL-Simple-ToField.html" rel="nofollow">ToField</a> instances for <a href="http://hackage.haskell.org/package/time-1.5.0.1/docs/Data-Time-Clock.html" rel="nofollow">NominalDiffTime</a>, in order to interface with a Postgres table with a column of type <code>interval</code>.</p>
  
  <p>I've found the <a href="http://hackage.haskell.org/package/postgresql-simple-0.4.10.0/docs/Database-PostgreSQL-Simple-TypeInfo-Static.html#v:interval" rel="nofollow">interval</a> TypeInfo and am in the process of figuring out how to interface with <code>TypeInfo</code>, but hopefully there is an easier way?</p>