pipes

Compositional pipelines

LTS Haskell 23.27:4.3.16@rev:6
Stackage Nightly 2025-07-06:4.3.16@rev:6
Latest on Hackage:4.3.16@rev:6

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BSD-3-Clause licensed by Gabriella Gonzalez
Maintained by [email protected]
This version can be pinned in stack with:pipes-4.3.16@sha256:f52626e8789a9918cb389383c6ecfbba898c94e1790b6fc7991a4e256350489b,3883

Module documentation for 4.3.16

pipes is a clean and powerful stream processing library that lets you build and connect reusable streaming components

Advantages over traditional streaming libraries:

  • Concise API: Use simple commands like for, (>->), await, and yield

  • Blazing fast: Implementation tuned for speed, including shortcut fusion

  • Lightweight Dependency: pipes is small and compiles very rapidly, including dependencies

  • Elegant semantics: Use practical category theory

  • ListT: Correct implementation of ListT that interconverts with pipes

  • Bidirectionality: Implement duplex channels

  • Extensive Documentation: Second to none!

Import Pipes to use the library.

Read Pipes.Tutorial for an extensive tutorial.

Changes

4.3.16

  • Fix example code for every
  • Improved documentation for ListT

4.3.15

  • Build against ghc-9.0

4.3.14

  • Add mapMaybe and wither, and more laws for filter and filterM.

4.3.13

  • Add MonadFail instance for Proxy

4.3.12

  • Fix space leak introduced in version 4.3.10
    • This leak primarily affects the use of forever

4.3.11

  • Fix documentation for scanM

4.3.10

  • Relax Monad constraints to Functor
  • Support GHC 8.8

4.3.9

  • Increase upper bound on exceptions

4.3.8

  • Increase upper bound on exceptions

4.3.7

  • Documentation fix

4.3.6

  • Fix implementation of pass in MonadWriter instance for Proxy

4.3.5

  • Support Semigroup being a super-class of Monoid

4.3.4

  • Increase upper bound on mmorph

4.3.3

  • Make X a synonym for Data.Void.Void

4.3.2

  • BUG FIX: Fix MMonad instance for ListT
    • The old instance was an infinite loop

4.3.1

  • Support building against ghc-7.4

4.3.0

  • BREAKING CHANGE: Remove Alternative/MonadPlus instances for Proxy
    • See commit 08e7302f43dbf2a40bd367c5ee73ee3367e17768 which explains why
  • Add Traversable instance for ListT
  • New MonadThrow/MonadCatch/MMonad/Semigroup/MonadZip instances for ListT
  • New MonadThrow/MonadCatch instances for Proxy
  • Fix lower bound on mtl
  • Increase upper bound on optparse-applicative

4.2.0

  • BREAKING CHANGE: Switch from ErrorT to ExceptT
  • Add Foldable instance for ListT
  • Fix all warnings
  • Enable foldr/build fusion for toList

4.1.9

  • Increase lower bound on criterion
  • Increase upper bound on transformers for tests/benchmarks
  • Optimize code by delaying INLINABLE annotations

4.1.8

  • Increase upper bound on transformers
  • Prepare for MRP (Monad of no Return Proposal)

4.1.7

  • Increase lower bound on deepseq
  • Add unfoldr
  • Add loop
  • Add toListM'
  • Improve efficiency of drop
  • License tutorial under Creative Commons license

4.1.6

  • Increase lower bound on base
  • Add diagrams to Pipes.Core documentation
  • Add mapM_
  • Add takeWhile'
  • Add seq
  • Improve efficiency of toListM

4.1.5

  • Increase upper bound on criterion

4.1.4

  • Increase upper bound on criterion
  • Add Monoid instance for Proxy

4.1.3

  • Increase lower bound on mtl
  • Re-export void
  • Add fold'
  • Add foldM'

4.1.2

  • Increase upper bounds on transformers and mtl

4.1.1

  • Add runListT
  • Add MMonad instance for Proxy
  • Add repeatM
  • Add laws to documentation of Pipes.Prelude utilities

4.1.0

  • Remove Haskell98 support
  • Use internal X type instead of Data.Void
  • Document Pipes.Lift module:w
  • Add drain
  • Add sequence

4.0.2

  • Improve performance of each
  • Add tutorial appendix explaining how to work around quadratic time complexity

4.0.1

  • Remove WriterT and RWST benchmarks
  • Add Enumerable instance for ErrorT
  • Add cabal flag for Haskell98 compilation
  • Add several rewrite rules
  • Add mtl instances for ListT
  • Fix implementation of pass, which did not satisfy Writer laws
  • Implement fail for ListT
  • Add type synonym table to tutorial appendix
  • Add QuickCheck tests for pipes laws
  • Add mapFoldable
  • Add Monoid instance for ListT
  • Add manual proofs of pipes laws in laws.md

4.0.0

Major upgrade of pipes to no longer use Proxy type class