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matz / streem


prototype of stream based programming language



Build Status Gitter

Streem is a stream based concurrent scripting language. It is based on a programming model similar to the shell, with influences from Ruby, Erlang, and other functional programming languages.

Note: Streem is still in the design stage. It's not working yet. Stay tuned.


In Streem, a simple cat program looks like this:

stdin | stdout

Streem is a (sort of) DSL for data flows. Above code means building data-flow connection between stdin and stdout. Actual data processing will be done in the event loop invoked after program execution.

For another example, a simple FizzBuzz will look like this:

seq(100) | {x ->
  if x % 15 == 0 {
  else if x % 3 == 0 {
  else if x % 5 == 0 {
  else {
} | stdout

The second part in the pipeline ({x ->...}) is a function object. If a function object is connected in the pipeline, it will be invoked for each element in the stream.


Installing dependencies

  • bison
  • flex
  • gcc / clang
  • libgc (libgc-dev on Debian/Ubuntu, bdw-gc on OSX homebrew)

Run make


Please note that Streem will not run any scripts yet, but you can check parse files and check syntax.


Send a pull request to We consider you have granted non-exclusive right to your contributed code under MIT license. Use for discussion.


MIT license (© 2015 Yukihiro Matsumoto)