valiant-pipes

Pipes streaming adapter for valiant.

Produces Producer r IO () values from query results, so they compose with the pipes ecosystem.

Quick start

import Valiant
import Valiant.Pipes
import Pipes
import Pipes.Prelude qualified as P

printAllUserNames :: Pool -> IO ()
printAllUserNames pool =
  withTransaction pool $ \tx ->
    runEffect $
      selectPipe (txConn tx) listAllUsers () 500
      >-> P.map userName
      >-> P.stdoutLn

Two streaming strategies

• selectPipe conn stmt params batchSize — cursor-based. Must run inside a transaction.
• foldPipe conn stmt params — single-shot extended-protocol query. No transaction required.

Both functions accumulate one result set at a time before yielding, so memory usage scales with the active batch (cursor) or the full result set (foldPipe). For truly incremental memory use, drive Valiant.withCursor / Valiant.fetchBatch directly.

See the valiant tutorial for Statement definitions and the valiant prepare workflow.