Doobie transact over a list of ConnectionIO programs

Question

Let's say I have a list of Doobie programs (all with Unit type parameters, fwiw):

val progList: List[ConnectionIO[Unit]] = prog1 :: prog2 :: ... :: Nil

Is there any way I can run them in one transaction? A for-comprehension won't work here, because I only know the precise composition of the program list at runtime. Essentially, I suppose I need to fold them together, I guess.

I suppose this question applies to Free Monads in Cats in general, so I'll tag Cats as well. Thanks.

@YuvalItzchakov Isn't that ticket about the reverse operation? — Alvaro Carrasco, Jul 29 '18 at 16:19

score 17 · Accepted Answer · answered Jul 29 '18 at 16:18

17

You can do that with .sequence from cats:

import doobie.implicits._
import cats.implicits._

...

val res = progList.sequence // ConnectionIO[List[Unit]]

answered Jul 29 '18 at 16:18

Alvaro Carrasco

6,103
16
24

Doobie transact over a list of ConnectionIO programs

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