ResumableFunctions

C# has a convenient way to create iterators using the yield return statement. The package ResumableFunctions provides the same functionality for the Julia language by introducing the @resumable and the @yield macros. These macros can be used to replace the Task switching functions produce and consume which were deprecated in Julia v0.6. Channels are the preferred way for inter-task communication in julia v0.6+, but their performance is subpar for iterator applications.

Build Status & Coverage

Installation

ResumableFunctions is a registered package and can be installed by running:

Pkg.add("ResumableFunctions")

Documentation

using ResumableFunctions

@resumable function fibonnaci(n::Int) :: Int
  a = 0
  b = 1
  for i in 1:n
    @yield a
    a, b = b, a+b
  end
end

for fib in fibonnaci(10)
  println(fib)
end

Licence & References

Authors

• Ben Lauwens, Royal Military Academy, Brussels, Belgium.

Contributing

• To discuss problems or feature requests, file an issue. For bugs, please include as much information as possible, including operating system, julia version, and version of MacroTools.
• To contribute, make a pull request. Contributions should include tests for any new features/bug fixes.

Release notes

• 2018: v0.4.2 prepare for Julia v1.1

  • better inference caused a problem;).
  • iterator with a specified rtype is fixed.

• 2018: v0.4.0 is Julia v1.0 compatible.

• 2018: v0.3.1 uses the new iteration protocol.

  • the new iteration protocol is used for a @resumable function based iterator.
  • the for loop transformation implements also the new iteration protocol.

• 2018: v0.3 is Julia v0.7 compatible.

  • introduction of let block to allow variables not te be persisted between @resumable function calls (EXPERIMENTAL).
  • the eltype of a @resumable function based iterator is its return type if specified, otherwise Any.

• 2018: v0.2 the iterator now behaves as a Python generator: only values that are explicitely yielded are generated; the return value is ignored and a warning is generated.

• 2017: v0.1 initial release that is Julia v0.6 compatible:

  • Introduction of the @resumable and the @yield macros.
  • A @resumable function generates a type that implements the iterator interface.
  • Parametric @resumable functions are supported.

Caveats

• In a try block only top level @yield statements are allowed.
• In a finally block a @yield statement is not allowed.
• An anonymous function can not contain a @yield statement.