This issue tracks any changes we want for v3.0.0. See the 3.0.0 branch.

The biggest change for now is a reimplementation of the Highland engine. See the original PR at #175.

Breaking changes

• Can no longer call fork after consume. Must call fork at the start.
• Can never consume a stream twice.
• The (undocumented) stream.source no longer exists.
• pipe passes along errors if piping to a Highland stream instead of calling this.emit('error') (Modifies pipe to pass along highland errors #166).
• wrapCallback and stream constructor passes an array for the default mapping hint when there are more than one argument is passed to the callback (Implement mappingHint for wrapCallback, fixes #246 #247, hintMapper default mapper should return array when more than one arg #335). See Reconsider making mappingHint's default mapper wrap in an array. #360 (comment)
• Renames and reargs (Highland v3.0.0 #179 (comment))
  • zipAll renamed to zipEach.
  • zipAll0 renamed to zipAll.
  • reduce and scan argument order reversed
• map will now throw an error if the argument is not a function. The old behavior instead mapped all stream elements to the argument if it was not a function.

Before release

• Implement onDestroy (see back-propagation of _.nil #172)
• Disable multiple consumes without a fork.
• Make sure all transforms correctly destroy their parent. Anything consume-based should get this for free, but not all transforms use consume. Maybe we should add a createDownstream method that does this for us.
  • merge
  • parallel
  • latest
  • sequence
  • flatten
  • reduce/reduce1
  • scan/scan1
• Create a test like noValueOnError to test the backpropagation behavior.
• Make pipe pass along errors to a Highland stream (Modifies pipe to pass along highland errors #166).
• Add a statement to the pipe docs pointing to through for the case when users want to pipe along errors as well as values to another Highland stream (Highland v3.0.0 #179 (comment)).
• Remove ConsumeStream and PipelineWrapperStream (to make it easier to port Extensibility 3.0 #337).
  • ConsumerStream
  • PipelineWrapperStream
• Port use (see Extensibility 3.0 #337).
• Create a test like noValueOnError to test that core transforms always return an object of the appropriate extended type.
• Docs for use.
• Fix default mapping hint behavior (hintMapper default mapper should return array when more than one arg #335). Remove the note in the docs that say we are changing the default behavior.
• Rename & reargs
  • reduce and scan
  • zipAll and zipAll0
  • pickBy
• Make map throw an error if not given a function (Map shouldn't accept a value. Move that to value() #404).
• Test that destroyed fork does not contribute backpressure (Highland v3.0.0 #179 (comment))
• Create highland-2 module for reverting the transform rename/reargs (Highland v3.0.0 #179 (comment))
• Split index.js into highland/core and highland/transforms
• Release the pending 2.x version.
• Merge 2.x into 3.0.0 once released.

Nice to have but can be delayed until after release

• Port over sync optimizations.
• Port over iterative consume and redirect.
• Check for memory leaks.
• Create some benchmarks.