Todo:

• Preload api / nested eager loading
  • Ecto Preload: https://hexdocs.pm/ecto/Ecto.Query.html#preload/3
  • Diesel BelongsTo: diesel-rs/diesel#89
  • Datomic Pull: https://docs.datomic.com/cloud/query/query-pull.html
  • Toucan Hydration: https://github.com/metabase/toucan/blob/master/docs/hydration.md
• Subqueries - handle by converting query to "table" with selection as fields? can't think of a typesafe way to handle this.

  sub := q.AsTable()
  q2 := From(subquery).Where(sub.IntField("boop").Eq(2))
  

• Partial selects - maybe structs are always fully hydrated, partial selects -> maps
• DB adapters - translate queries to eg go-pg queries
• Generate concrete field types
• Fragment escape hatch - support injecting raw sql snippets
• Function expressions
• Cast expressions
• Grouping / Aggregates