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streamly v0.7.0 Release Notes

Release Date: 2019-11-01 // about 4 years ago

  • 💥 Breaking changes

    • 🔄 Change the signature of foldrM to ensure that it is lazy
    • 🔄 Change the signature of iterateM to ensure that it is lazy.
    • scanx would now require an additional Monad m constraint.

    Behavior change

    • Earlier ParallelT was unaffected by maxBuffer directive, now maxBuffer can limit the buffer of a ParallelT stream as well. When the buffer becomes full, the producer threads block.
    • 0️⃣ ParallelT streams no longer have an unlimited buffer by default. Now the buffer for parallel streams is limited to 1500 by default, the same as other concurrent stream types.

    🗄 Deprecations

    • In Streamly.Prelude:

      • runStream has been replaced by drain
      • runN has been replaced by drainN
      • runWhile has been replaced by drainWhile
      • fromHandle has been deprecated. Please use Streamly.FileSystem.Handle.read, Streamly.Data.Unicode.Stream.decodeUtf8 and splitOnSuffix with Streamly.Data.Fold.toList to split the stream to a stream of String separated by a newline.
      • toHandle has been deprecated. Please use intersperse and concatUnfold to add newlines to a stream, Streamly.Data.Unicode.Stream.encodeUtf8 for encoding and Streamly.FileSystem.Handle.write for writing to a file handle.
      • Deprecate scanx, foldx, foldxM, foldr1
      • Remove deprecated APIs foldl, foldlM
      • Replace deprecated API scan with a new signature, to scan using Fold.

    • In Streamly module:

      • runStream has been deprecated, please use Streamly.Prelude.drain

    • ✂ Remove deprecated module Streamly.Time (moved to Streamly.Internal.Data.Time)

    • ✂ Remove module Streamly.Internal (functionality moved to the Internal hierarchy)

    🐛 Bug Fixes

    • 🛠 Fix a bug that caused uniq function to yield the same element twice.
    • 🛠 Fix a bug that caused "thread blocked indefinitely in an MVar operation" exception in a parallel stream.
    • 🛠 Fix unbounded memory usage (leak) in parallel combinator. The bug manifests when large streams are combined using parallel.

    Major Enhancements

    🚀 This release contains a lot of new features and major enhancements. For more 👀 details on the new features described below please see the haddock docs of the modules on hackage.

    👻 Exception Handling

    👀 See Streamly.Prelude for new exception handling combinators like before, after, bracket, onException, finally, handle etc.

    Composable Folds

    Streamly.Data.Fold module provides composable folds (stream consumers). Folds 👍 allow splitting, grouping, partitioning, unzipping and nesting a stream onto multiple folds without breaking the stream. Combinators are provided for 👍 temporal and spatial window based fold operations, for example, to support ⏱ folding and aggregating data for timeout or inactivity based sessions.

    Composable Unfolds

    Streamly.Data.Unfold module provides composable stream generators. Unfolds allow 🐎 high performance merging/flattening/combining of stream generators.

    Streaming File IO

    Streamly.FileSystem.Handle provides handle based streaming file IO operations.

    Streaming Network IO

    • Streamly.Network.Socket provides socket based streaming network IO operations.

    • 🏗 Streamly.Network.Inet.TCP provides combinators to build Inet/TCP clients and servers.

    Concurrent concatMap

    The new concatMapWith in Streamly.Prelude combinator performs a 🔀 concatMap using a supplied merge/concat strategy. This is a very powerful combinator as you can, for example, concat streams concurrently using this.

    Other Enhancements

    • ➕ Add the following new features/modules:

      • Unicode Strings: Streamly.Data.Unicode.Stream module provides encoding/decoding of character streams and other character stream operations.
      • Arrays: Streamly.Memory.Array module provides arrays for efficient in-memory buffering and efficient interfacing with IO.

    • ➕ Add the following to Streamly.Prelude:

      • unfold, fold, scan and postscan
      • concatUnfold to concat a stream after unfolding each element
      • intervalsOf and chunksOf
      • splitOn, splitOnSuffix, splitWithSuffix, and wordsBy
      • groups, groupsBy and groupsByRolling
      • postscanl' and postscanlM'
      • intersperse intersperse an element in between consecutive elements in stream
      • trace combinator maps a monadic function on a stream just for side effects
      • tap redirects a copy of the stream to a Fold