Support Redis pipelines

[MurrayGroves]

Right now Valkyrie doesn't support Redis pipelines, which allow commands to be chained together without waiting for a server response between each command.

This means running some commands together looks like this:

use _ <- try(valkyrie.custom(conn, ["MULTI"], 1000))
use _ <- try(valkyrie.del(conn, [subreddit_key],1000))
use _ <- try(valkyrie.rpush(conn, subreddit_key, text_only, 1000))
use _ <- try(valkyrie.custom(conn, ["EXEC"], 1000))

Perhaps pipeline support would look something like this?

use _ <- try(valkyrie.pipe(conn, 4000)
  |> valkyrie.custom(["MULTI"])
  |> valkyrie.del([subreddit_key])
  |> valkyrie.rpush(subreddit_key, text_only)
  |> valkyrie.custom(["EXEC"])
)

[isaacharrisholt]

Implementing pipelining would be quite a large task as it'd probably need a new API that doesn't execute commands immediately, and everything would likely have to be returned as strings to satisfy the type system. It would likely look something like this:

let result: Result(List(Result(String, valkyrie.Error)), pipeline.Error) = pipeline.new(conn, 4000)
  |> pipeline.del([subreddit_key])
  |> pipeline.rpush(subreddit_key, text_only)
  |> pipeline.exec()

There would also likely be a pipeline.exec_transaction() to execute in a transaction by wrapping with MULTI/EXEC.

Does this sound reasonable?

[MurrayGroves]

Seems reasonable to me!

[isaacharrisholt]

@MurrayGroves would you mind looking at #10 and giving me your opinion?

[MurrayGroves]

Looks great to me, but worth considering I've only been programming in Gleam for a week!