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prototype of stream based programming language
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examples add splat in pattern matching and array construction Jul 13, 2016
src Update pull request #165 (better conditional) May 1, 2018
.gitignore use bison/flex generated header files Apr 1, 2015
LICENSE should update copyright year in LICENSE file; fix #7 Dec 11, 2014
Makefile invoke make via $(MAKE) make variable Jul 6, 2015 Now we can run scripts with streem Apr 25, 2018


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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.


Installing dependencies

  • bison
  • flex
  • gcc / clang

Run make



In Streem, a simple cat program looks like this:

stdin | stdout

You can try it out by (firstly cd to streem top directory):

$ bin/streem -e 'stdin | stdout'


$ bin/streem examples/01cat.strm

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) returns a stream of numbers from 1 to 100.
# A function object in pipeline works as a map function.
# stdout is an output destination.
seq(100) | map{x->
  if (x % 15 == 0)     "FizzBuzz"
  else if (x % 3 == 0) "Fizz"
  else if (x % 5 == 0) "Buzz"
  else                 x
} | 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.

There are more examples under folder examples/. Just play with them!


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 (© 2015-2016 Yukihiro Matsumoto)

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