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GHC 9.10.3 · lts/ghc-9.10.x · c74966e · 2026-09-27

Modulelinear-base-0.4.0Haskell2010

Streaming.Prelude.Linear

The names exported by this module are closely modeled on those in Prelude and Data.List, but also on Pipes.Prelude, Pipes.Group and Pipes.Parse. The module may be said to give independent expression to the conception of Producer / Source / Generator manipulation articulated in the latter two modules. Because we dispense with piping and conduiting, the distinction between all of these modules collapses. Some things are lost but much is gained: on the one hand, everything comes much closer to ordinary beginning Haskell programming and, on the other, acquires the plasticity of programming directly with a general free monad type. The leading type, Stream (Of a) m r is chosen to permit an api that is as close as possible to that of Data.List and the Prelude.

Import qualified thus:

import Streaming
import qualified Streaming.Prelude as S

For the examples below, one sometimes needs

import Streaming.Prelude (each, yield, next, mapped, stdoutLn, stdinLn)
import Data.Function ((&))

Other libraries that come up in passing are

import qualified Control.Foldl as L -- cabal install foldl
import qualified Pipes as P
import qualified Pipes.Prelude as P
import qualified System.IO as IO

Here are some correspondences between the types employed here and elsewhere:

              streaming             |            pipes               |       conduit       |  io-streams
-------------------------------------------------------------------------------------------------------------------
Stream (Of a) m ()                  | Producer a m ()                | Source m a          | InputStream a
                                    | ListT m a                      | ConduitM () o m ()  | Generator r ()
-------------------------------------------------------------------------------------------------------------------
Stream (Of a) m r                   | Producer a m r                 | ConduitM () o m r   | Generator a r
-------------------------------------------------------------------------------------------------------------------
Stream (Of a) m (Stream (Of a) m r) | Producer a m (Producer a m r)  |
--------------------------------------------------------------------------------------------------------------------
Stream (Stream (Of a) m) r          | FreeT (Producer a m) m r       |
--------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------
ByteString m ()                     | Producer ByteString m ()       | Source m ByteString  | InputStream ByteString
--------------------------------------------------------------------------------------------------------------------

    module Streaming.Linear.Internal.Type

    module Streaming.Linear.Internal.Consume

    module Streaming.Linear.Internal.Interop

    module Streaming.Linear.Internal.Many

    module Streaming.Linear.Internal.Process

    module Streaming.Linear.Internal.Produce